Let's count the number of sweets each one has using the statements (parenthesis besides shows the number of sweets each has then):
Sue:
She has 18 (18)
She gives x to Tony (18 - x)
She eats 5 (18 - x - 5)
In total Sue has (18 - x - 5) = 13 - x
Tony:
He has 18 (18)
He gets x from Sue (18 + x)
He eats half of what he has. So half is remaining ([tex]\frac{18+x}{2}[/tex]
In total Tony now has [tex]\frac{18+x}{2}[/tex]
ANSWER: Sue has [tex]13-x[/tex] sweets & Tony has [tex]\frac{18+x}{2}[/tex] sweets
