- A and
- B and
- C and
- D
Step-by-Step Solution
Cost = (number of bats)(price of a bat) + (number of balls)(price of a ball), matched to the correct total. Option 2 swaps the roles of bat and ball, option 3 swaps the two totals, and option 4 lumps both purchases into a single equation — one equation in two unknowns can never pin down both prices. (Solving gives )
Answer: A) and