The equivalent rational number of $\frac{5}{7}$, whose numerator is 45 is 

Given rational number is $\frac{5}{7}$ 

Multiplying the numerator and the denominator with 9 we get, 

$\frac{5\times 9}{7\times 9}=\frac{45}{63}$ 

Hence, The equivalent rational number of $\frac{5}{7}$, whose numerator is 45 is $$\frac{45}{63}$$.