let say
e=number of english teachers
m=number of math teachers
3 more english tahn math
e=m+3
ratio if e to m is 6:5
e:m=6:5
e/m=6/5
e=m+3
(m+3)/m=6/5
times 5m both sides
5(m+3)=6m
5m+15=6m
minus 5m both sides
15=m
e=m+3
e=15+3
e=18
18 englihs
15 math