How do answer 3/ 1/ 3/4 (3 divided by 1 over 3/4)

 I'm not 100% but I think the answer is 4.

(3 /1) / (3 /4)      change to multiplication and  invert the second fraction

(3 /1) * (4 / 3)   = 4    ...... just as Anonymous found !!!

$${\frac{{\mathtt{3}}}{{\mathtt{1}}}} = {\mathtt{3}}$$

$${\frac{{\mathtt{3}}}{\left({\frac{{\mathtt{3}}}{{\mathtt{4}}}}\right)}} = {\mathtt{4}}$$

Easy