In July, David gave his wife, Zara, $2500 for household expenditure. Zara spent 50% of the sum on rental, 20% on food and saved the rest. In August, David reduced the sum he gave to Zara. Zara spent the same amount on rental and reduced the amount she spent on food by 20%. She saved the remaining 25% of the sum given to her in August. By what percentage was the sum given to Zara reduced by?

	Rental	Food	Savings	Total
Before	50%	20%	30%	$2500
Change		- 4%	- ?	- ?
After	50%	16%
Comparing the amounts spent in August	75 u		25 u	100 u

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

Amount that David reduced on food in percent
= 20% x 20%
= ²⁰₁₀₀ x 20
= 4%

Total amount that David spent on rental and food in percent
= 50% + 16%
= 66%

100% → 2500

1% → 2500 ÷ 100 = 25

66% → 66 x  25 = 1650

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

75 u = 66% 

75 u = 1650

1 u = 1650 ÷ 75 = 22

Amount that David gave to Zara in August
= 100 u
= 100 x 22
= $2200

Amount that Zara received less from David from July to August
= 2500 - 2200
= $300

Percentage that the sum given to Zara was reduced by from July to August
= ³⁰⁰₂₅₀₀ x 100%
= 12%

Answer(s): 12%