How can writing phrases as algebraic expression you when solving problems?

Writing phrases can help you visulize the problem more clearly than just doing mental math,this can help you get a question right 99.9% than just mental math.I usally write down the problem and,aleays get it write if i do not do the work i only get 1/2 of the marks.

Idon’t know how to do that

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