-16=-3(7a+8)
multiply the bracket by -3
(-3)(7)=-21
(-3)(80=-24
-16=-21a-24
move -24 to the other side
sign changes from -24 to +24
-16+24=-21a-24+24
8=-21a
divide both sides by -21 to get a by itself
8/-21=-21a/-21
answer:
a=-8/21
