Needing help with the formula to be able to prove these answers to be correct. What are the steps ?

Question

Moesha's is ( 3G + 1 ) years old and Shanti is twice Moesha's age.

A ) Find the sum of the ages of Moesha's and Shanti in2 years time.

Answer
The sum of their ages is ( 9g + 7 ) year in 2 years time.

B) How old will Shanti be when Moesha's age is twice her present age?

Answer
Shanti will be ( 9g + 3 ) years old

C) Find how old Moesha's and Shanti we're 4 years ago if g = 5

Answer
Moesha's = 12 years old Shanti = 28 years old.

Thank you :)

Answer 1

Right now:
Moesha is (3G+1) years old.
Shanti is 2(3G+1) or (6G+2).

A. Sum = ((3G+1)+2) + ((6G+2)+2) = (9G+7) Years.

B. Diff. = (6G+2) - (3G+1) = (3G+1).
Shanti = (6G+2) + (3G+1) = (9G+3) Years old.

C. Moesha = (3G+1)-4 = (3*5+1)-4 = 12 years old.
Shanti = (6G+2)-4 = ?.