Answer
a. 1200-0.07x
b. 780
Work Step by Step
a.
0.05x+1200-0.12x
Combine like terms to simplify the equation
1200-0.07x
b.
1200-0.07x
Using the equation you simplified in part a, substitute 6000 for x to get the total interest.
1200-0.07(6000)
=1200-420
=780