Final answer:
The coach will need to buy 6 soccer balls after the parents' contribution, spending a total of $77.94 before taxes.
Step-by-step explanation:
The question involves basic arithmetic to calculate the total cost of purchasing soccer balls for a coach's team after factoring in the contribution of four volunteer parents.
The coach initially needs to buy 18 soccer balls, one for each player. With 4 parents agreeing to buy 3 balls each, they would collectively buy 4 parents * 3 balls/parent = 12 balls. Therefore, the coach would need to buy the remaining balls, which is 18 total balls - 12 balls bought by parents = 6 balls.
Next, to calculate the total cost for the remaining balls, we multiply the number of balls the coach needs to buy by the price per ball: 6 balls * $12.99/ball = $77.94. Thus, the coach will spend $77.94 on soccer balls before taxes.