Answer:
69×7=60×7+9×7 and if 10×7=70 then 6×70=420 and 9×7=70-7=63
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)
The line below are parallel so they have same slopes
If the green line has a slope of -1/2, the slope of the red line is also - 1/2
Answer
-1/2
Your answer is 2/5 theoretically
