Question

At Billy's preschool, they have a total of 25 bicycles and tricycles. Among them all, there are 57 wheels. How many of each are there?

Answer 1

let x be the number of bicycles and y the number of tricycles. x+y=25 (1) and 2x+3y=57 (2). Multiplying (1) by 2, you have 2x+2y=50. Doing (2)-(1) gives y=7. Therefore, x=25-7=18. There are 18 bicycles and 7 tricycles.