1) - 3(4s+5) + 7(2s – 6) = 10s – 20

Expand the terms: $$-12s - 15 + 14s - 42 = 10s - 20$$.

Combine like terms on the left side: $$2s - 57 = 10s - 20$$.

Isolate s: $$-37 = 8s$$, so $$s = -37/8$$.