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

	Rental	Food	Savings	Total
Before	50%	20%	30%	$8000
Change		- 2%	- ?	- ?
After	50%	18%
Comparing the amounts spent in March	80 u		20 u	100 u

Amount that Andy saved in percent
= 100% - 50% - 20%
= 30%

Amount that Andy reduced on food in percent
= 10% x 20%
= ¹⁰₁₀₀ x 20
= 2%

Total amount that Andy spent on rental and food in percent
= 50% + 18%
= 68%

100% → 8000

1% → 8000 ÷ 100 = 80

68% → 68 x  80 = 5440

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

80 u = 68% 

80 u = 5440

1 u = 5440 ÷ 80 = 68

Amount that Andy gave to Kimberly in March
= 100 u
= 100 x 68
= $6800

Amount that Kimberly received less from Andy from February to March
= 8000 - 6800
= $1200

Percentage that the sum given to Kimberly was reduced by from February to March
= ¹²⁰⁰₈₀₀₀ x 100%
= 15%

Answer(s): 15%