3 added to five times a number, and the result is multiplied by 4 . The final result is 72 . What is the number

What is the missing step in this proof ?

A.s.a.! similarity in right triangles, refer to the figure to complete this proportionc/a = a/? a.) cb.) hc.) rd.) s

Whats are the trickiest steps to do when adding or subtracting rational expressions? how does knowledge of rational numbers u in adding and subtracting rational expressions?