Question

A box containing 10 physics textbooks and 3 physics workbooks weighs 50.1 pounds. A box containing 8 physics textbooks and 12 physics workbooks weighs 51.9 pounds. The weight of each box when empty is 1.5 pounds. So how many does each textbook and each workbook weigh? Explain how u solved this problem.

Answer 1

10x + 3y + 1,5 = 50,1 * (- 4) ⇒ -40x-12y-6 = -200,4
8x + 12y + 1,5 = 51,9
combine
8x-40x+12y-12y+1.5-6=51.9-200.4  *(-1)⇔
32x+4.5=148.5
32x=148.5-4.5
x=144/32
x=4.5 (textbook)
10*4.5+3y+1.5=50.1
3y+46.5=50.1
3y=3.6
y=1.2 (workbook)