Problem: solving word problems
Staples recently charged $17.99 per box of Pilot roller ball pens and $7.49 per box
for Bic matic mechanical pencils. If Kelling Community College purchased 120 boxes
for a total of $1234.80 how many boxes of each did they purchase?
x = number of boxes of Pilot pens
y = number of boxes of Bic pencils
x + y = 120
17.99x + 7.49y = 1234.80
x + y = 120
y = -x + 120
17.99x + 7.49y = 1234.80
17.99x + 7.49(-x + 120) = 1234.80
17.99x - 7.49x + 898.80 = 1234.80
10.5x + 898.80 = 1234.80
10.5x + 898.80 - 898.80 = 1234.80 - 898.80
10.5x = 336
10.5x/10.5 = 336/10.5
x = 32
y = -x + 120
y = -32 + 120
y = 88
17.99x + 7.49y = 1234.80
17.99(32) + 7.49(88) = 1234.80
575.68 + 659.12 = 1234.80
1234.80 = 1234.80
Answer: 32 boxes of Pilot pens, 88 boxes of Bic pencils