Question

At a convention of monsters, 2/5 have no horns, 1/7 have one horn, 1/3 have two horns, and the remaining 26 have three or more horns. How many monsters are attending the convention?

Answer 1

If we take it that, the total amount is say hmmm "x"
then one can say that $\bf \begin{cases} \cfrac{2}{5}x\impliedby &\textit{no horns}\\\\ \cfrac{1}{7}x\impliedby &\textit{one horn}\\\\ \cfrac{1}{3}x\impliedby &\textit{two horns}\\\\ 26\impliedby &remaining \end{cases} \\\\\\ \textit{so the total is really }\quad \cfrac{2}{5}x+\cfrac{1}{7}x+\cfrac{1}{3}x+26$

add up the fractions of "x" and the constant of 26