I'll walk you through the 1st one. Then you can apply that model to the 2nd one.
Using the remainder theorem,
Now, solve the three equation using your favorite method of solving a system of 3 equations in 3 unknowns. I used matrices and found a = 2, b = -13, and c = 15. You could use Cramer's Rule or substitution or something else.
Substituting these back into , we get: