Part A
Since each ticket costs $8, we need to add $8 for each plus ticket one buys:
Therefore, we have:
Part B
Notice that, instead of summing (8+8+8+...) we can multiply $8 by the number of tickets bought m to obtain the total cost c.
Thus, we have:
Part C
The equation above (c = m x $8) shows that the total cost c depends on the number of tickets bought.
However, we write that relation in another way:
Thus, if we know the total cost, we can divide it by $8 to find the number of tickets bought. Then, we can say that the number of tickets boght m depends on the total cost c.
Therefore, both thoughts are correct.