Answer:
Older brother = 15
Younger brother = 3
Step-by-step explanation:
Let the present age of the older brother = x
Let the present age of the younger brother = y
x + 3 = 3(y+ 3) Remove the brackets
x + 3 = 3y +9
x + y = 18 Solve for x
y = 18 - x Put this value into the top equation
x + 3 = 3(18 - x) + 9
x + 3 = 54 - 3x + 9
x + 3 = 63 - 3x Add 3x to both sides
x + 3x + 3 = 63 Subtract 3 from both sides. Combine the xs
4x = 63 - 3
4x = 60 Divide by 4
4x/4 = 60/4
x = 15
x + y = 18
15 + y = 18
y = 3
