index cards for a total cost of $55.40. Find the cost of one box of paper clips and the cost of one package of index cards. in progress 0 3 months 2021-07-24T14:10:34+00:00 1 Answers 6 views 0 Answers ( ) 1. Answer: paper clips =$1.85

index cards = $3.95 Step-by-step explanation: Mark 12 paper clips = x 10 index cards = y$61.70 total

Janice

15 paper clips = x

7 index cards = y

\$55.40 total

12x + 10y = 61.70

15x + 7y   = 55.40

*** you want to cancel out one of the letters

(12x + 10y = 61.70) * -7

(15x + 7y   = 55.40) * 10

-84x -70y = -431.9

150x + 70y = 554.0

150x + 70y = 554.0

-84x -70y = -431.9

66x + 0 = 122.1

66x = 122.1

x = 122.1 ÷ 66

x = 1.85

plug it back in

15(1.85) + 7y   = 55.40

27.75 + 7y   = 55.40

7y   = 55.40 – 27.75

7y = 27.65

y = 27.65 ÷ 7

y = 3.95