Answer:
Choice A.
Step-by-step explanation:
Let x = price of a helmet, y = price of a bat, z = price of a ball.
Company A can provide 9 helmets, 6 bats, and 12 balls for $525.
9x + 6y + 12z = 525
Company B can provide 10 helmets, 8 bats, and 10 balls for $600.
10x + 8y + 10z = 600
Company C can provide 8 helmets, 5 bats, and 15 balls for $500.
8x + 5y + 15z = 500
Answer: Choice A.
