A coffee shop sells lattes for $4 and cappuccinos for $3. Last Friday, they sold 78 drinks for a total of $252. How many cappuccinos were sold?

60 cappuccinos were sold.

Explanation:
x = number of lattes sold
y = number of cappuccinos sold

Two equations can be set up:
x + y = 78
4x + 3y = 252

The first equation can be rearranged and substituted into the other equation to find the value of a variable.

y = 78 - x
4x + 3(78 - x) = 252
4x + 234 - 3x = 252
x + 234 = 252
x = 18

To find y, the value of x can be substituted into either equation.

x + y = 78
18 + y = 78
y = 60

To check answers, substitute both values into the original equations and make sure they work.

x + y = 78
18 + 60 = 78
78 = 78

4x + 3y = 252
4(18) + 3(60) = 252
72 + 180 = 252
252 = 252