Okay. Basically, a is greater than or equal to 9.
First, you do distribute the 2.
8a+2-10a(< or =)20
Subtract two on both sides.
8a-10a(< or =)18
Then subtract 10a from 8a
-2a(< or =)18
Divide by two on both sides
and switch around the greater than sign since you divided by a -2
a(> or =)-9
And if you check, -9 works, -8 works, and -10 doesn't work.