Answer:
The competitive market equilibrium wage is $ 10 per hour.
The competitive market equilibrium quantity of labor is 70 thousand workers.
With a minimum wage of $ 12 per hour, the surplus will be 20 thousand workers.
Step-by-step explanation:
We set up the equation system:

If Ld = Ls then:
100 - 3w = 7w
100 = 10w
100/10 = w = 10
and now we solve for L
L = 100 - 3*10 = 100-30 = 70
L = 7*10 = 70
(II)
If w = 12
Ld 100 - 3*12 = 64
Ls 7*12 = 84
Surplus 20 thousands