Question

If 9:7 is the ratio, there are here 116 more boys than girls how many total students are there

Answer 1

Now, let's say there are "b" boys and "g" gals... ok... well, we know there are 116 more boys than gals..... so, if there are "g" gals then there must be "g + 116" boys.

$\bf \cfrac{boys}{girls}\qquad 9:7\qquad \cfrac{9}{7}\implies \cfrac{9}{7}=\cfrac{\stackrel{boys}{g+116}}{\stackrel{girls}{g}}\implies 9g=7g+812 \\\\\\ 2g=812\implies g=\cfrac{812}{2}\implies g=\stackrel{girls}{406}$

what's the total class?  well is g + b or g + ( g + 116).