Answer:
S = 13 - x
T = (18 + x) / 2
Explanation:
S = 18
T= 18
Sue gives away x, so subtract it from 18. But Tony gets x, so add it to 18 in his expression.
S = 18 - x
T= 18 + x
Sue eats 5 so subtract 5 from her expression. Tony eats half, so divide his expression by 2.
S = 18 - x - 5
T = 18 + x / 2
Simplify 18-5.
S = 13 - x
T = (18 + x) / 2