.
The condition gives you two equations
T - B = 2, (1)
(T+6)*(B+6) - T*B = 120. (2)
Simplify eq(2):
T*B + 6B + 6T + 36 - T*B = 120,
6B + 6T = 120 - 36 = 84,
T + B =
= 14.
Thus the modified system of equation is THIS:
T - B = 2 (3)
T + B = 14 (4)
Add the equations (3) and (4). You will get
2T = 2 + 14 = 16. Hence, T =
= 8.
Then from (4), B = 14 - T = 14 - 8 = 6.
Answer. Tom is 8 years old. His brother is 6 years old.
Check. (8+6)*(6+6) - 8*6 = 120. ! Correct !