In May, Sam gave his wife, Penelope, $3000 for household expenditure. Penelope spent 60% of the sum on rental, 30% on food and saved the rest. In June, Sam reduced the sum he gave to Penelope. Penelope 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 June. By what percentage was the sum given to Penelope reduced by?

	Rental	Food	Savings	Total
Before	60%	30%	10%	$3000
Change		- 9%	- ?	- ?
After	60%	21%
Comparing the amounts spent in June	90 u		10 u	100 u

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

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

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

100% → 3000

1% → 3000 ÷ 100 = 30

81% → 81 x  30 = 2430

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

90 u = 81% 

90 u = 2430

1 u = 2430 ÷ 90 = 27

Amount that Sam gave to Penelope in June
= 100 u
= 100 x 27
= $2700

Amount that Penelope received less from Sam from May to June
= 3000 - 2700
= $300

Percentage that the sum given to Penelope was reduced by from May to June
= ³⁰⁰₃₀₀₀ x 100%
= 10%

Answer(s): 10%