x =7.5 this is because you would cross multiply to get 12x=90. You would have to isolate the variable by dividing both sides by 12. that leaves you with x=7.5
First solve the numerical side: 9/4 = 2.25 So now we know: 3x/10 = 2.25 Multiply both sides by 10: 3x/10 x 10 = 2.25 x 10 Simplify it: 3x = 22.5 Divide both sides by 3: 3x/3 = 22.5/3 Simplify it: x = 7.5
