ANSWER
Find out the what is the range of ink cartridges he can buy and still have enough money left over for the reams of paper.
To proof
let us assume that the number of the ink cartridges buy be x.
As given
Carlos monthly office supply budget is $250.
He needs to buy ink cartridges which cost $40 a piece.
He will need to save at least $50 of his budget for reams of paper.
than the inequality is written in the form
x ≤ 5
the range of the ink cartridges he can buy be 0 ≤ x ≤ 5 when he saves
at least $50 of his budget for reams of paper.
Hence proved