Question

at a school the number of boys: number of girls = 11 : 9
there are 124 more boys than girls

work out the total number of students at the school

Answer 1

b = boys

g = girls

$b:g=11:9, b=g+124$

$b=11g/9$

Insert in the second equation

$11g/9=g+124$

Solve for g

$11g=9g+124\cdot9$

$2g=124\cdot9\implies g=62\cdot9=\boxed{558}$

Solve for b

$b=g+124=\boxed{682}$

Hope this helps.