A certain number of persons can finish a piece of work in 100 days . If there were 10 persons less, it would take 10 more days finish the work. How many persons were there originally?

As per given question,
8 persons can build a wall 140 meter long in 42 days.
1 persons can build a wall 140 meter long in 42 x 8 days.
1 persons can build a wall 1 meter long in 42 x 8 / 140 days.
30 persons can build a wall 1 meter long in 42 x 8 / 30 x 140 days.
30 persons can build a wall 100 meter long in 42 x 8 x 100 / 30 x 140 days.
30 persons can build a wall 100 meter long in 42 x 8 / 3 x 14 days.
30 persons can build a wall 100 meter long in 42 x 8 / 42 days.
30 persons can build a wall 100 meter long in 8 days.

0.6 cm represents 6.6 km in a scale.
1 cm represents 6.6 / 0.6 km in a scale.
80.5 cm represents 6.6 x 80.5 / 0.6 km in a scale.
80.5 cm represents 11 x 80.5 km in a scale.
80.5 cm represents 885.5 km in a scale.

As we know that,
1 Dozen = 12 piece
49 Dozen = 49 x 12 piece
Price of 357 apples is Rs. 1517.25.
Price of 1 apples is Rs. 1517.25 / 357.
Price of 49 x 12 apples is Rs. 1517.25 x 49 x 12 / 357.
Price of 49 x 12 apples is Rs. 1517.25 x 7 x 12 / 51.
Price of 49 x 12 apples is Rs. 1517.25 x 7 x 4 / 17.
Price of 49 x 12 apples is Rs. 2499.
So Price will be around 2500 and answer will be 2500.

As per given question,
In 1 minute, 6 identical machines can produce a total of 270 bottles.
In 1 minute, 1 identical machines can produce a total of 270 / 6 bottles.
In 1 minute, 10 identical machines can produce a total of 270 x 10 / 6 bottles.
In 4 minute, 10 identical machines can produce a total of 270 x 10 x 4 / 6 bottles.
In 4 minute, 10 identical machines can produce a total of 45 x 10 x 4 bottles.
In 4 minute, 10 identical machines can produce a total of 1800 bottles.

16 men working 7 hours day can plough a field in 48 days.
1 men working 7 hours day can plough a field in 48 x 16 days.
1 men working 1 hours day can plough a field in 48 x 16 x 7 days.
14 men working 1 hours day can plough a field in 48 x 16 x 7 / 14 days.
14 men working 12 hours day can plough a field in 48 x 16 x 7 / 14 x 12 days.
14 men working 12 hours day can plough a field in 48 x 16 / 2 x 12 days.
14 men working 12 hours day can plough a field in 48 x 4 / 2 x 3 days.
14 men working 12 hours day can plough a field in 48 x 2 / 3 days.
14 men working 12 hours day can plough a field in 16 x 2 = 32 days.

Let the remaining food will last for D days.
500 men had provisions for (27 ? 3) = 24 days.
( 500 + 300 ) men had provisions for D days.
More men, Less days ( Indirect Proportion )
we can write as :-
? 800 : 500 :: 24 : x ? (800 × D ) =( 500 × 24 )
? ( 500 × 24 ) /800 =15
Therefore , 15 days is correct answer .

Suppose the food will last for D days at same rate .
250 men had provisions for 40 days.
( 250 - 50 ) men had provisions for D days.
Less men, More days ( Indirect Proportion )
we can write as :-
? 200 : 250 :: 40 : D ? (200 × D ) =( 250 × 40 )
? ( 250 × 40 ) /200 = 50
Therefore , 50 days is required answer .

According to question ,
3 pumps working in 2 days = 8 × 2 = 16 hours
It means that they can empty a tank in 16 hours .
3 pumps 1 hour work = 1/16
1 pumps 1 hour work = 1/( 3 × 16 )
4 pumps 1 hour work =4 × 1/( 3 × 16 ) = 1 / 12
Hence , they will empty the tank in 12 hours .

Let us assume that each soldier eats one unit of food per day. Thus, total units of food at the beginning will be 1000 x 30 = 30000.
After 10 days 1000 soldiers would have eaten 1000 x 10 = 10000 units of food. Thus food left after 10 days equals 20000 units. Now, there are total of 2000 soldiers who eat one unit of food every day. So, the number of days that 20000 units of food will serve 2000 soldiers is 20000/2000 = 10