Simplify 39.96% of 649.85 ÷ 13.07 = 45.14 - ?

This can be easily simplified by Approximation process

Given 39.96% of 649.85  $÷$13.07 = 45.14 - ? can be written as 

40% of 650  $÷$13 = 45 - ?

$\frac{\frac{40 x 650}{100}}{13} = 45 - ?? = 45 - 20? = 25.$