In August, Ken gave his wife, Risa, $10000 for household expenditure. Risa spent 60% of the sum on rental, 20% on food and saved the rest. In September, Ken reduced the sum he gave to Risa. Risa spent the same amount on rental and reduced the amount she spent on food by 20%. She saved the remaining 20% of the sum given to her in September. By what percentage was the sum given to Risa reduced by?

	Rental	Food	Savings	Total
Before	60%	20%	20%	$10000
Change		- 4%	- ?	- ?
After	60%	16%
Comparing the amounts spent in September	80 u		20 u	100 u

Amount that Ken saved in percent
= 100% - 60% - 20%
= 20%

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

Total amount that Ken spent on rental and food in percent
= 60% + 16%
= 76%

100% → 10000

1% → 10000 ÷ 100 = 100

76% → 76 x  100 = 7600

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

80 u = 76% 

80 u = 7600

1 u = 7600 ÷ 80 = 95

Amount that Ken gave to Risa in September
= 100 u
= 100 x 95
= $9500

Amount that Risa received less from Ken from August to September
= 10000 - 9500
= $500

Percentage that the sum given to Risa was reduced by from August to September
= ⁵⁰⁰₁₀₀₀₀ x 100%
= 5%

Answer(s): 5%