1 Cancel m.
12i=c*m/s
2 Use rule a*b/c = ab/c
12i=cm/s
3 Multiply both sides by s.
12is=cm
4 Divide both sides by 12.
is=cm/12
5 Divide both sides by i
s=cm/12/i
6 Simplify cm/12/i
s=sm/12i