Chapter P, Prerequisites - Section P.9 - Modeling with Equations - P.9 Exercises - Page 71: 35

$9$ of each coin.

Let the amount of each coin be $m$. Then, $x+5x+10x$ is the value of the coins, which the problem stated was $144$. Set up the equation $(1+5+10)x=144$. Solving for $x$, $x=\frac{144}{(1+5+10)}=\frac{144}{16}=9$ of each coin.