In September, Oliver gave his wife, Irene, $8000 for household expenditure. Irene spent 50% of the sum on rental, 10% on food and saved the rest. In October, Oliver reduced the sum he gave to Irene. Irene spent the same amount on rental and reduced the amount she spent on food by 30%. She saved the remaining 20% of the sum given to her in October. By what percentage was the sum given to Irene reduced by?

	Rental	Food	Savings	Total
Before	50%	10%	40%	$8000
Change		- 3%	- ?	- ?
After	50%	7%
Comparing the amounts spent in October	80 u		20 u	100 u

Amount that Oliver saved in percent
= 100% - 50% - 10%
= 40%

Amount that Oliver reduced on food in percent
= 30% x 10%
= ³⁰₁₀₀ x 10
= 3%

Total amount that Oliver spent on rental and food in percent
= 50% + 7%
= 57%

100% → 8000

1% → 8000 ÷ 100 = 80

57% → 57 x  80 = 4560

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

80 u = 57% 

80 u = 4560

1 u = 4560 ÷ 80 = 57

Amount that Oliver gave to Irene in October
= 100 u
= 100 x 57
= $5700

Amount that Irene received less from Oliver from September to October
= 8000 - 5700
= $2300

Percentage that the sum given to Irene was reduced by from September to October
= ²³⁰⁰₈₀₀₀ x 100%
= 28.75%

Answer(s): 28.75%