Answer:
Step-by-step explanation:
If there were 3 vans for every 7 cars, then there were 3 vans for every 10 of the total in the lot. Use a proportion to solve this:
[tex]\frac{vans}{total}:\frac{3}{10}=\frac{x}{150}[/tex] and cross multiply to get
10x = 450
so x = 45
There are 45 vans in the lot.