150 vehicles had passed Luann.
There are:
=> 6 cars
=> 10 trucks
=> 14 SUV
=> 15 minivans.
How many minivans would we expect to pass out of 150?
=> 6 + 10 + 14 + 15 = 45
=> 15 / 45 = x / 150, where 15 is the number of minivans, and 45 is the total number of vehicles that passed
=> 150 / 45 = 3.333333… repeating decimals
=> 3.333… * 15 = 50
x = 50, there will be 50 minivans that will pass in LUann