Answer: 110 blue cars and 88 brown cars
====================================================
Work Shown:
x = number of blue cars
198-x = number of brown cars
The ratio of blue to brown is 5 to 4, meaning,
(x blue)/(198-x brown) = (5 blue)/(4 brown)
x/(198-x) = 5/4
4x = 5(198-x) .... cross multiply
4x = 990-5x
4x+5x = 990
9x = 990
x = 990/9
x = 110 blue cars were made
198-x = 198-110 = 88 brown cars were made.
---------------
Check:
(110 blue)/(88 brown) = 110/88 = (22*5)/(22*4) = 5/4
This shows the ratio "110 blue to 88 brown" reduces fully to "5 blue to 4 brown". It confirms we have the correct answers.