what is the algebra problem 7/b-36=a/72=28/b

Question

i need the answer to this question

Answer 1

Split into two equations:

(1) 7/(b-36)=28/b to solve for b, and (2) a/72=28/b to solve for a.

(1) 7/(b-36)=28/b, cross-multiply:

7b=28(b-36), divide through by 7:

b=4(b-36), b=4b-144, 144=3b, b=144/3=48.

(2) a/72=28/b, cross multiply:

ab=72×28, a=72×28/b=72×28/48=3×28/2=3×14=42.

CHECK using a/72=7/(b-36).

LHS=a/72=42/72=7/12; RHS=7/(b-36)=7/(48-36)=7/12.

So LHS=RHS confirms that a=42 and b=48.