math
posted by Evelyn .
Lily went for 8 rides at the county fair. Some rides were on the merrygoround, and the rest were on the pirate ship. The total cost of all rides was $6.30. Each pirate ship ride cost $0.60, and each merrygoround cost $0.90. How many pirate ship did Lily take?

X Rides on merrygoround.
Y Rides on pirate ships.
Eq1: X + Y = 8 Rides.
Eq2: 0.9X + 0.6Y = 6.30.
Multiply Eq1 by 0.9:
0.9X  0.9Y =  7.20.
0.9X + 0.6Y = 6.30.
Add the Eqs and get:
0.3Y = 0.9,
Divide both sides by 0.3:
Y  3 Pirate ship rides.