Raul can spend not more than $ 38.22 on the pair of jeans
<em><u>Solution:</u></em>
Raul plans to spend no more than $78.00 on two shirts and a pair of jeans
He bought the two shirts for $19.89 each
Therefore,
cost of 2 shirts = 19.89 x 2 = $ 39.78
Let "x" be the cost of pair of jeans
Then we frame a inequality as:
cost of 2 shirts + cost of pair of jeans
78

Here we have used "less than or equal to" symbol, because he spend no more than $ 78
Solve the inequality for "x"

Thus, he can spend not more than $ 38.22 on the pair of jeans