Max went to the fair with 5 friends.some paid $2 each to ride the bumper cars.the rest paid $3 each to ride the roller coaster.they spent $16 in all.how many rode each ride ?

I have 2 questions, one of them should reveal a problem in the problem:

1. Are you sure there are 5 friends?

2. Are you sure they spent $16 dollars?

Because, as the problem is, I'm getting -1 friends rode the bumper cars and 6 people rode the roller coaster, so obviously something is wrong, here's my work:

a = Friends that rode bumper cars

b = Friends that rode the roller coaster

???