Ziggy sells coffee and donuts , the total number of cofees and donuts ziggy sells today is 100. ziggy charges 3$ for coffee and 1$ per donut and made 180 today. how many coffees and donuts did he sell?

You use a system of equations
x= coffee
y= donuts
x+y=100
3x+y=180
there’s 3 ways to solve system of equations substitution graphing and elimination. it would be easiest to use substitution here. So you multiply x+y=100 by -1 so it become -x-y=-100. then you combine it with the other equation and get 2x=80 so x=40 which means 40 cups of coffee were sold then you plug it back in to find y. 40+y=100. y=60.
y= 60 (donuts). x= 40 (coffee)