A man donated 5% of his income to a charitable organisation and deposited 20% of the remainder in a bank. If he now has Rs. 1919 left, what is his income?

Let salary be Rs. A, then A - 15 % of A - 30% of 85% of A = 2380
? A - 15A/100 - (30 x 85 x A)/(100 x 100) = 2380
? 200A - 30A - 51A = 2380 x 200
? 119A = 2380 x 200
? A = (2380 x 200)/199 = 4000

CP of the chair which is sold at 25% of profit = Rs 4000/ (1+ 25%)
= Rs 4000/1.25
= Rs 3200

Now given, that sum of CP pf table and chair= sum of SP of table and Chair
? 8000= 3200 + CP of Table
? CP of Table = Rs 4800
? Loss on Cost price of table = Rs 4800- Rs 4000= Rs 8000
? Loss % = 8000/4800 = 16.66%

10% of 100 = 10
New price = 110

Again, 10% of 110 = 110 x (10/100) = 11
New price = 110 + 11 = 121

? Required increment = 121 - 100 = 21

Given, a = 20%
Required percentage = [a/(100 - a)] x 100%
= [20/(100 - 20)] x 100%
= (20/80) x 100%
= 25%

Saving = 20%
Expenditure = 80% = ?6000

Since 80% is 6000 so 20% would be 6000/4 = ?1500
Hence net saving per month = ?1500

? 137¹/₂% of N = 33
? {(275/2) x N} / 100 = 33
? N = (33 x 2 x 100) / 275 = 24

? 72¹/₂% of N = 87
? {(145/2) x N} / 100 = 87
? N = (87 x 2 x 100) / 145 = 120

Let third number be N
Then, first number = 70% of N = 7N/10 and,
Second number = 63% of N = 63N/100
Difference = 7N/10 - 63N/100 = 7N/100
? Required percentage = (7N/100) x (10/7N) x 100 % = 10%

? (62% of N - 38% of N) =144
? 24% of N = 144
? N = (144 x 100)/24 = 600

Reduction in consumption = (20/120) x 100% = 50/3%
? Reduction in consumption /Original consumption = (50/3) / 100 = 1/6 = 1 : 6