If you have two numbers A*F and B*F such that their greatest common factor is F, their least common multiple will be A*F*B. Dividing the LCM by F will give A*B. The sum of the two numbers will be A*F+B*F = F(A+B).

Factors of 200/10 = 20 that add to 90/10 = 9 are 4 and 5.

Factors of 200/10 = 20 that add to 90/10 = 9 are 4 and 5.