SOLUTION: Crystallina spent her entire $ 20 weekly allowance on books and candy last week. This week she did the same, but she spent 50 % more on candy and 12.5 % less on books.How much did

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Question 252128: Crystallina spent her entire $ 20 weekly allowance on books and candy last week. This week she did the same, but she spent 50 % more on candy and 12.5 % less on books.How much did she spend on candy this week?
Answer by dabanfield(803) About Me  (Show Source):
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Crystallina spent her entire $ 20 weekly allowance on books and candy last week. This week she did the same, but she spent 50 % more on candy and 12.5 % less on books.How much did she spend on candy this week?
Let x be the amount she spent the first week on books and y the amount on candy.
Then:
x + y = 20 or
y = 20 - x
The second week then we have:
.875x + 1.5y = 20
Substituting 20-x for y in the second equation we have:
.875*x + 1.5*(20 - x) = 20
Solve for x and then calculate y = 20 - x.