Answer
$20a^2-3a-56$
Work Step by Step
RECALL
For any real numbers a, b, and c:
$a(b+c)=ab + ac \\AND
\\a(b-c) =ac-bc$
Use the distributive property (which is shown above) to obtain:
$=4a(5a+8) -7(5a+8)
\\=4a(5a) + 4a(8) -7(5a) - 7(8)
\\=20a^2+32a-35a-56
\\=20a^2-3a-56$
