A fleet of kids on scooters (2 wheels) and tricycles went whizzing by Igor’s workshop. He was quick enough to count 7 kids and 19 wheels. How many tricycles were there?
If all 7 kids had been on tricycles, there would have been 21 wheels. Since there were only 19 wheels, two kids must have been on scooters.
Check: 2(2) + 5(3) = 19.