In August, Zane gave his wife, Xandra, $9000 for household expenditure. Xandra spent 60% of the sum on rental, 30% on food and saved the rest. In September, Zane reduced the sum he gave to Xandra. Xandra 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 September. By what percentage was the sum given to Xandra reduced by?

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

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

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

Total amount that Zane 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 Zane spent on rental and food is repeated. 

90 u = 81% 

90 u = 7290

1 u = 7290 ÷ 90 = 81

Amount that Zane gave to Xandra in September
= 100 u
= 100 x 81
= $8100

Amount that Xandra received less from Zane from August to September
= 9000 - 8100
= $900

Percentage that the sum given to Xandra was reduced by from August to September
= ⁹⁰⁰₉₀₀₀ x 100%
= 10%

Answer(s): 10%