a.) 0.35x + 42 ≤ 70
She wants the truck for one day, which will cost $45. We don't know how far the truck is traveling so that is the variable. She cannot spend more than $70, since that is her budget.
b.) Solve for x using the above equation:
0.35x + 42 ≤ 70
0.35x ≤ 28
x ≤ 80
Judy can drive 80 miles