Given that opposite sides of a parallelogram are equal, whereby side AB is congruent to side CD and side BC is congruent to side DA and also that side AC is congruent to side CA, we have;
Triangle ABC with sides AB, BC, and AC is congruent to triangle CDA with corresponding sides CD, DA, and CA, by the Side-Side-Side (SSS) rule of congruency (two or more triangles that have all three sides of one triangle congruent to the three sides of the other triangle are congruent).
8 girls to every 3 boys. You can make an equation to solve this: 8x + 3x = 528. 528 = 11x. Then divide 528 by 11 to get 48. x=48. 8(48) = 384 girls. 3(48) = 144 boys.