The solution to this problem requires two equations.
First let x= the number of hot dogs, and y = the number of sodas
Then $1.50x + $0.50y = $78.50
Second, we know that x + y = 87
We then solve the second equation for x, which is x = 87 - y
We substitute that value into the first equation, which gives us
$1.50(87 - y) + $0.50y = $78.50;
we get $130.5 - $1.50y + $0.50y = $78.50; after we combine all the factors, we get y = 52
substituting that value into equation 2, we get x = 35
So, x = 35 and y = 52
Checking our work using the first equation,
$1.50(35) + $0.50(52) = $78.50