Answer
a). The expression 0.05 x + 0.12(10000-x) can be simplified as 1200 - 0.07 x
b). Total interest at the end of one year = 780
Work Step by Step
a). The expression 0.05 x + 0.12(10000-x) can be simplified as
0.05 x + 0.12(10000-x) = 0.05 x + 1200 - 0.12 x
= 1200 - 0.07 x
simplified expression is = 1200 - 0.07 x
b).given x = 6000
total interest at te end of one year = 1200 - 0.07 $\times$ 6000
=1200 - 420
=780
