so the ratio of boys to girls is 12:24.. now, is that an equivalent ratio as 2 boys for 4 girls? or 2:4? let's see.
[tex]\bf \cfrac{boys}{girls}\qquad 12:24\qquad \cfrac{12}{24}\implies \boxed{\cfrac{1}{2}}
\\\\\\
\cfrac{boys}{girls}\qquad 2:4\qquad \cfrac{2}{4}\implies \boxed{\cfrac{1}{2}}[/tex]
you could start simplifying the 12/24 fraction by dividing by some common multiple, say 2, and get 6/12, then divide by 3 and get 2/4 and stop there.
then you'll notice that 12/24 is really 2/4 in disguise.
