8 months; $740
75x+140=90x+20
Find x then plug it in to find the cost
We are given the system of equations -:

Since the second equation is y-isolated equation. It can be substituted as y = 6x+22 in the first equation.

Expand 3 in the expression so we can combine like terms and isolate x-variable.

Then combine like terms.

Get rid of 66 from the left side by subtracting both sides by itself.

To finally isolate the variable, divide both sides by 20 so we can leave x only on the left side.

Simplify to the simplest form.

Normally, we have to find the y-value too but since we only find x-value. The answer is x = -4.
Answer
I hope this helps! If you have any questions or doubts regarding my answer, explanation or system of equations, feel free to ask!
let apple juice = x
milk = 2x
fruit punch = 3x
3x + 2x + x = 660
6x = 660
x = 660/6
x = 110 apple juices
2*110 = 220 milks
3*110 = 330 fruit punches
45 times the numerator plus the denominator is most likely going to equal the same amount as if it were doubled.
You simplify the fraction by dividing 2 to the nominator and the denominator. So 24/2=12, 8/2=4, 6/2=3. You can only divide a root with a root number so in this case the root three doesn't get affected