Answer:
The child can sell 15 cookies and 30 lemonade glasses, or 10 cookies and 40 glasses of lemonade, etc
Step-by-step explanation:
If the child wants to make $30 and gets $1 per cookie and $0.50 per lemonade glass, he could sell 15 cookies and 30 glasses, 10 cookies and 40 glasses, etc. He has to sell at least 5 cookies, though, as the lemonade is only worth $25.