We are given : Cost of a gallon of milk = $2.50.
Cost of a cup of yogurt = $1.20.
Total money Monica has = $20.
Number of cups of yogurt Monica can buy = x.
And inequality made is also correct
1.20x + 2.5 ≤ 20.
Now, we need to solve it for x.
Subtracting 2.5 from both sides, we get
1.20x + 2.5 -2.5 ≤ 20 - 2.5.
1.20x ≤ 17.5
Dividing both sides by 1.20, we get
1.20x/1.20 ≤ 17.5/1.20.
x ≤ 14.5833...
Because it's less than 15, so final answer is : 14 is greatest number of cups of yogurt Monica can buy.
