Question

A class of 19 pupils has five more girls than boys. Let n = the number of boys.

n + (n + 19) = 5

n + (n + 5) = 19

n - (n + 5) = 19

n + (n - 19) = 5

Answer 1

n+(n+19)=5

Answer 2

n+(n+19)=5
-19 -19
n+n=-14
2n=-14
2n/2 (crosses out the 2 which just leaves the n)
2n/2=-14/2
n=-7

I don't know if that's right.. but you could mess around with it

Answer 3

and the rest are the same way. if I did it right..