Answer: he should have 348 cars and 173 trucks.
Explanation:
Let x represent the number of cars that he should have.
Let y represent the number of trucks that he should have.
He has room on his lot for 521 vehicles. It means that
x + y = 521- - - - -- - - - -1
Ramon has 175 more more cars than trucks. It means that
x = y + 175
Substituting x = y + 175 into equation 1, it becomes
y + 175 + y = 521
2y = 521 - 175 = 346
y = 346/2
y = 173
x = y + 175 = 173 + 175
x = 348