2x + 3 = 7. What is x?

After June bought 3 apples, she has $5 left. If June has $8 dollars initially, which is the correct equation to find out the cost of an apple? (a = Apple)

June bought 4 apples that cost her $8. 3 oranges and 2 apples cost June $13. How much does an orange cost?

Tommy bought 4 apples and 3 oranges and it cost him $10. Tommy later bought 3 oranges and 5 apples and it cost him $11. How much does each orange and apple cost?

After buying 2 bicycles and 3 carts, John’s father spent $120. Tom’s father spent $110 to buy 3 bicyles and 1 cart. How much does each bicycle and cart cost?