First isolate the variable x in 3x+2=15. Subtract 2 from both sides so that you get 3x=13. Divide 3 by both sides and you get x=4 1/3. Since you keep the same value as x then you substitute in 4 1/3 in 9x+5 so that it looks like 9(4 1/3)+5 which would then equal to 44. Choice 3 would be correct.
