A store sold 28 pairs of cross-trainer shoes for a total of $2,220. Style A sold for $70 per pair and Style B sold for $90 per pair. How many of each style were sold?

Style A sold 15 pairs while Style B sold 13 pairs

Step-by-step explanation:

Let the number of Style A pairs be A.

Let the number of Style B pairs be B.

The store sold 28 pairs of cross-trainer shoes for a total of $2,220 and Style A sold for $70 per pair while Style B sold for $90 per pair.

This implies 2 things:

A + B = 28 (1)

and

(70*A) + (90*B) = 2220

=> 70A + 90B = 2220 (2)

We now have two simultaneous equations:

A + B = 28 (1)

70A + 90B = 2220 (2)

From (1):

A = 28 - B (3)

Put (3) in (2):

70(28 - B) + 90B = 2220

1960 - 70B + 90B = 2220

1960 + 20B = 2220

Collecting like terms:

20B = 2220 - 1960

20B = 260

B = 260 / 20

B = 13

Therefore:

A = 28 - 13 = 15

Style A sold 15 pairs while Style B sold 13 pairs.

lockers 1, 4, 9, 16, 25, 40, and 49 are open

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