well, if you add the numbers 3+1 you get 4. from this we know that there are 4 units total. 36÷4=9 so each unit is equal to 9. we can multiply 9•3 to get 27. there are 27 boys. we can multiply 9•1 to get 9 girls. subtracting 9 from 27, we get 18 more boys that girls.
