# Question #dd112

There are $24$ dessert recipies and $48$ recipies for main dishes.
Reading the problem, I wrote two equations. The first is that $d$(dessert) $+ m$(main) $= 72$. Then, I wrote that $2 d = m$, or that there are twice as many dessert recipes as there are main ones.
Now, we use substitution to solve. If $m = 2 d$, then we insert $2 d$ where $m$ was, chnaging $d + m = 72$ to $d + 2 d = 72$. This becomes $3 d = 72$. By dividing by $3$, we see that $d = 24$.
If $d = 24$, then $24 + m = 72$. Subtract by $24$ on both sides, and we just found the value of $m$, which is $48$. Thus, there are $48$ main dish recipies and $24$ dessert dishes.