Answer
20
Work Step by Step
Make a system of equations. There are 2 entrees, and we will use the variable x for the number of people that bought 15 dollar one, and y for the number of people who bought the 18 dollar one. This equation models how much money was made
$15x + 18y = 606$
Each of 37 people choose and got one of the 2 entrees.
$x + y = 37$
Solve this. You can use any method to solve, but I will use graphing. After solving, as shown below, you will see that $(20,17)$ is the solution. This means that 20 fifteen dollar entrees were ordered
