In June, Luis gave his wife, Marion, $9000 for household expenditure. Marion spent 60% of the sum on rental, 30% on food and saved the rest. In July, Luis reduced the sum he gave to Marion. Marion spent the same amount on rental and reduced the amount she spent on food by 30%. She saved the remaining 10% of the sum given to her in July. By what percentage was the sum given to Marion reduced by?

	Rental	Food	Savings	Total
Before	60%	30%	10%	$9000
Change		- 9%	- ?	- ?
After	60%	21%
Comparing the amounts spent in July	90 u		10 u	100 u

Amount that Luis saved in percent
= 100% - 60% - 30%
= 10%

Amount that Luis reduced on food in percent
= 30% x 30%
= ³⁰₁₀₀ x 30
= 9%

Total amount that Luis spent on rental and food in percent
= 60% + 21%
= 81%

100% → 9000

1% → 9000 ÷ 100 = 90

81% → 81 x  90 = 7290

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

90 u = 81% 

90 u = 7290

1 u = 7290 ÷ 90 = 81

Amount that Luis gave to Marion in July
= 100 u
= 100 x 81
= $8100

Amount that Marion received less from Luis from June to July
= 9000 - 8100
= $900

Percentage that the sum given to Marion was reduced by from June to July
= ⁹⁰⁰₉₀₀₀ x 100%
= 10%

Answer(s): 10%