we will take the least number as x and the largest as x+2 and the 2nd biggest as x+1
3x-2=x+2
3x=x+2+2
3x=x+4
3x-x=4
2x=4
x=2
x=2
x+1=3
x+2=4
we shall check whether it is right
just replace the x
3x-2=x+2
3*2-2=2+2
6-2=4
4=4
therefore the answer 2,3 and 4 is correct