Three hikers A, B and C start on a trip with ? 50 each and agree to share the expenses equally. If at the end of the trip, A has ? 20 left with him, B ? 30 and ? 40, by how much amount must they settle their accounts?

Let the expenditure and saving be ? 26y and ? 3y, respectively.
Then, according to the question,
26y + 3y = 7250
? 29y = 7250
? y = 7250/29
? y = 250
So, his monthly saving is (250 x 3) i., e ? 750

Let the present age of mother be x and daughter be y.

From question,
(x - 1)/(y - 1) = 4/1
? x - 1 = 4(y - 1)
? x = 4y - 3 ......(i)

Again from question,
(x + 4)/(y + 4) = 3/1
? x + 4 = 3(y + 4)
? x = 3y + 8 ..(ii)

On Solving Eqs. (i) and (ii), we get y = 11 and x = 41
? Ratio of their ages 5 yr ago = (x - 5)/(y - 5) = 36/6 = 6/1 = 6 : 1

Work done by (x + 2 ) men in (x - 3) days = (x + 2) (x - 3)
Work done by x men in (x - 2) days = x(x - 2)
? (x + 2) (x - 3) = x(x - 2)
On Solving, we get x = 6

Floppy - days = Number of floppies X Days run
Here, A's floppy - days : B 's floppy - days : C's floppy - days = A's payment for rent : B 's payment for rent : C's payment for rent
= 27 x 19 : 21 x 17 : 24 x 23
A's rent : B's rent : C's rent = 171 : 119 : 184
? Payment for rent by A = [171/(171 + 119 + 184)] x 23700 = ? 8550

Let the salaries of Laxman and Gopal one year before be x₁ ,y₁ respectively.
? x₁/y₁ = 3/4 ......(1)
x₂ + y₂ = 4160 .....(2)

From equations (1) and (2)
x₂ = Rs. 1600.

A : B = 1¹/₂ = 3 : 2 = 3 x 7 : 2 x 7 = 21 : 14
B : C = 1³/₄ : 1 = 7 : 4 = 7 x 2 : 4 x 2 = 14 : 8
? A : B : C = 21 : 14 : 8
? C's share = [8/(21 + 14 + 8)] x 1290 = ? 240

Profit of A/Profit of B = (Amount x Number of months) / (Amount x Number of months)
= (10000 x 12)/(5000 x 8) = 3/1
? Profit share of A = [3/(3 + 1)] x 2000 = ? 1500

Students in the first class / Students in second class = (40 - 30)/(30 - 25) = 10/5 = 2/1
? Students in first class = 2 x 30 = 60

Milk = (2/3) x 60 = 40 L
Water = (1/3) x 60 = 20 L
Water added = W L
Now, 40/(20 + W) = 1/2
? W = 60 L

Let the number of boys and girls are 7k and 5k, respectively.
Given, total number of students = 2400
? 7k + 5k = 2400
? 12k = 2400
? k = 200
? Required number of girls = 5k = 5 x 200 = 1000