Sagot :
Let x = eraser
x + 5 = pad paper
x + 7 = pencil
x+x+5+x+7 = 42
3x + 12 = 42
3x = 42-12
3x = 30
3x/3 = 30/3
x = 10
Eraser = x
Eraser = 10
Pad paper = x + 5
PP = 10 + 5
PP = 15
Pencil = x + 7
Pencil = 10 + 7
Pencil = 17
10+15+17 = 42