30 girls , 12 were selected
40 boys, 16 were selected
We can simplify these down by finding the Greatest Common Factor in both girls and boys:
30:12 .... 15:6 .... 1 : 2.5 30/12 .... 15/6 .... 2.5
40:16 .... 20:8 .... 1 : 2.5 OR 40/16 .... 20/8 .... 2.5
They are equal ratios because their most simplified ratios/fractions are equivalent
