Step-by-step explanation:
t is the number of ride tickets she can buy.
=>
[tex]15 + t \times 0.5 \leqslant 24[/tex]
she has to pay $15 just for entering. the rest of the money she can use for ride tickets.
so, whatever she does, she has to stay inside the $24 limit, as she does not have more money.
the $15 admission goes off the $24 available money. that leaves $9.
each ride ticket costs $0.50, so she can buy max. 9/0.5 = 18 tickets. she can buy fewer tickets, but she cannot buy more than these 18 tickets.
so, again
[tex]15 + t \times 0.5 \leqslant 24[/tex]
[tex]t \times 0.5 \leqslant 24 - 15 = 9[/tex]
[tex]t \times 0.5 \leqslant 9[/tex]
[tex]t \leqslant 9 \div 0.5 = 9 \div (1 \div 2) = 2 \times 9 \div 1 \\ = 18[/tex]
[tex]t \leqslant 18[/tex]
