Find values for m and b so that the system has two solutions

{y=x^2
{y=mx+b

Aflute is on sale for 20% off. including the discount and 8% tax, the sales price is $216.

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?

Jose predicted that he would sell 48 umbrellas. he actually sold 72 umbrellas. what are the values of a and b in the table below? round to the nearest tenth if necessary