[tex]\text{First I would recommend replacing the question mark with x}\\\text{We have two ratios, }\\\text{and we need to solve that hard-looking equation}\\\text{in terms of x}[/tex]
[tex]\rule{300}{1.7}[/tex]
[tex]\text{We can multiply x times 36:: 36x}\\\text{We can multiply 4 times 27:: 108}[/tex]
[tex]\rule{300}{1.7}[/tex]
[tex]\text{Now it's easier to solve for x:: 36x=108; x=3}\\\text{ (we divided by 36 on both sides of the = sign)}[/tex]
[tex]\rule{300}{1.7}[/tex]
[tex]\text{The missing number is 3}[/tex]
