A grocer has two kinds of candies, one selling for 40 cents a pound and the other for $1.40 per pound. How many pounds of each kind must he use to make 100 pounds worth 85 cents a pound?

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Step-by-step explanation:

Candy x = 0.90 per pound 

Candy y = 0.40 per pound

100 pounds * 0.85 per pound = 85

x + y = 100

0.90x + 0.40y = 85

x = 100 - y

0.90(100 - y) + 0.40y = 85

90 - 0.90y + 0.40y = 85

-0.50y = 85 - 90

y = -5 / -0.50

y = 10

x = 100 - y

x = 100 - 10

x = 90

0.90x + 0.40y = 85

0.90(90) + 0.40(10) = 85

81 + 4 = 85

85 = 85

ca = ec

cpctc makes it so that corresponding parts of the triangle you proved to be equal are equal, the other options aren't part of the part of the triangles you proved to be equal.