Same-side interior angles are formed when a transversal line intersects two or more parallel lines. In this case,Line FC can be taken as a transversal line cuting parallel lines CD and FG thus making angles ACD and GFC same side interior angles.
Consecutive angles ACD and GFC are supplementary.This means they add up to 180°.
Let x be the number of girls at the beach. The ratio of boys to girls at the beach cleanup was 7 : 8. If there were 42 boys and x girls, you can write a proportion: