Apply the distributive property to factor out the greatest common factor. 55+35

To factor out the greatest common factor, you need to first list them out:
35: 1, 5, 7, 25
55: 1, 5, 11, 55

As you can see, the greatest common factor here is 5.
Which means:
5(11 + 7)

There is 240 red cars and there is 400 blue cars because 240/3=80 and 80*5=400