Answer:
He must use 3 GB or less
Step-by-step explanation:
Total cost = flat fee + number of GB * charge per GB
We know he must stay under 30 dollars so change the equals to less than or equal to (the opening facing the 30) and replace the total cost with 30
30≥ flat fee + number of GB * charge per GB
We know the flat fee is 21 and the charge per GB is 3
30≥ 21 + number of GB * 3
Subtract 21 from each side
30-21 ≥ 21-21 + number of GB * 3
9≥number of GB * 3
Divide by 3
9/3 ≥ number of GB * 3/3
3≥ number of GB
He must use 3 GB or less
