If y=2.25x is a direct proportion and why?

Abike shop sells you a bicycle for $63 and a helmet for $21. the total cost is 150% of what the shop spent originally. how much did the shop spend originally? how much profit did the bike shop earn by selling the bicycle and helmet to you ?

What value of x is in the solution set of 4x - 12 s 16 + 8x? -10 -9 -8 -7

What is the best way to answer questions with a x expression in the question. for example 3x + 10x=?