24) 5(x+y) 7 / 63 3(x+y) =

$$\frac{5(x+y)}{63} \cdot \frac{7}{3(x+y)} = \frac{5 \cdot 7}{63 \cdot 3} = \frac{5 \cdot 1}{9 \cdot 3} = \frac{5}{27}$$