The three terms x+12, 3x+5 and 2x+25 are the first three terms of an arithmetic progression. What is the value of x?

Solve X by finding common difference....in this case;step 1:3X+5-(X+12)=2X+25-(3X+5)

step2:3X+5-X-12=2X+25-3X-5
step3:solve like terms n u'll remain with 3X=27 n then make X subject of the formular by dividing each term by 3...n u'll remain with X= 9