P = printer
M = microwave
Weight Equation: 20P + 30M = 1600
Size equation: 3P + 2M = 150
Solve Weight Equation:
20P + 30M = 1600
Subtract 30M from each side:
20P = 1600 - 30M
Divide both sides by 20:
P = 80 - 3/2M
Replace P in size equation with above:
3(80 - 3/2M) + 2M = 150
240 - 4.5M + 2M = 150
240-2.5M = 150
Subtract 240 from each side:
-2.5M = -90
Divide both sides by -2.5:
M = 36
Now solve for P:
3P + 2(36) = 150
3P = 72 = 150
3P = 78
P = 78/3
P = 26
26 Printers and 36 Microwaves.
