In September, Oscar gave his wife, Abi, $3500 for household expenditure. Abi spent 50% of the sum on rental, 20% on food and saved the rest. In October, Oscar reduced the sum he gave to Abi. Abi spent the same amount on rental and reduced the amount she spent on food by 30%. She saved the remaining 20% of the sum given to her in October. By what percentage was the sum given to Abi reduced by?

	Rental	Food	Savings	Total
Before	50%	20%	30%	$3500
Change		- 6%	- ?	- ?
After	50%	14%
Comparing the amounts spent in October	80 u		20 u	100 u

Amount that Oscar saved in percent
= 100% - 50% - 20%
= 30%

Amount that Oscar reduced on food in percent
= 30% x 20%
= ³⁰₁₀₀ x 20
= 6%

Total amount that Oscar spent on rental and food in percent
= 50% + 14%
= 64%

100% → 3500

1% → 3500 ÷ 100 = 35

64% → 64 x  35 = 2240

The total amount that Oscar spent on rental and food is repeated. 

80 u = 64% 

80 u = 2240

1 u = 2240 ÷ 80 = 28

Amount that Oscar gave to Abi in October
= 100 u
= 100 x 28
= $2800

Amount that Abi received less from Oscar from September to October
= 3500 - 2800
= $700

Percentage that the sum given to Abi was reduced by from September to October
= ⁷⁰⁰₃₅₀₀ x 100%
= 20%

Answer(s): 20%