Karen paid 1.20 for 6 pencils and 4 erasers at the school store. Trey paid 1.10 for 8 pencils and 2 erasers at the same store. How much does a pencil cost? How much does an eraser cost?
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Karen paid 1.20 for 6 pencils and 4 erasers at the school store. Trey paid 1.10 for 8 pencils and 2 erasers at the same store. How much does a pencil cost? How much does an eraser cost?
1.20 for 6 pencils and 4 erasers —>> 6P + 4E = 1.20 (equation 1)
1.10 for 8 pencils and 2 erasers —>> 8P + 2E = 1.10 (equation 2)
multiply both sides (eq 2) by 2 16P + 4E = 2.20 (eq 3)
and subtract (eq 1) from it 6P + 4E = 1.20 (eq 1)
10P = 1.00
P = 0.10 Pencils are 10¢ apiece
substitute 10¢ back into (eq 1) (6)(0.10) + 4E = 1.20
0.60 + 4E = 1.20
4E = 0.60
E = 0.15 Erasers are 15¢ apiece
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