how do i solve 3/5=3s/10-12

3/5 = (3s/10) - 12

3/5 + 12 = 3s/10

3/5 + (12*5 / 5) = 3s/10

63/5 = 3s/10

(63/5)*10 = 3s

126 = 3s

s = 126/3

s = 42.