1.1 #24

T = tons of 2-min film developers

S = tons of 6-min film developers

N = tons of 9-min film developers

Plant A equation:  6T + 12S + 12N = 600 min (10 hours)
Plant B equation: 24T + 12S + 12N = 960 min (16 hours)

Eliminating S & N gives:  18T = 360 ==> T = 20 tons
Substituting into the plant A equation gives

S + N = (600 - 120)/12 = 40 tons

We conclude that T = 20 tons and S & N are any two nonnegative
numbers that add to 40 tons.