Answer:
Maggie's age is 13 years
Step-by-step explanation:
Let
x ------> Maggie's brother age
y ------> Maggie's age
we know that
x+y=43 ------ > equation A
x=3y-9 ------> equation B
substitute equation B in equation A and solve for y
(3y-9)+y=43
4y=43+9
4y=52
y=13
therefore
Maggie's age is 13 years
