In June, Tim gave his wife, Tina, $4000 for household expenditure. Tina spent 70% of the sum on rental, 10% on food and saved the rest. In July, Tim reduced the sum he gave to Tina. Tina 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 July. By what percentage was the sum given to Tina reduced by?

	Rental	Food	Savings	Total
Before	70%	10%	20%	$4000
Change		- 2%	- ?	- ?
After	70%	8%
Comparing the amounts spent in July	80 u		20 u	100 u

Amount that Tim saved in percent
= 100% - 70% - 10%
= 20%

Amount that Tim reduced on food in percent
= 20% x 10%
= ²⁰₁₀₀ x 10
= 2%

Total amount that Tim spent on rental and food in percent
= 70% + 8%
= 78%

100% → 4000

1% → 4000 ÷ 100 = 40

78% → 78 x  40 = 3120

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

80 u = 78% 

80 u = 3120

1 u = 3120 ÷ 80 = 39

Amount that Tim gave to Tina in July
= 100 u
= 100 x 39
= $3900

Amount that Tina received less from Tim from June to July
= 4000 - 3900
= $100

Percentage that the sum given to Tina was reduced by from June to July
= ¹⁰⁰₄₀₀₀ x 100%
= 2.5%

Answer(s): 2.5%