So first we add 15 to get X by itself . So here : 2X-15=85
+15 +15
Then the 15’s cancel out and u left with 2X=85+15
85+15=100
2X=100
Then we have to get rid of the 2 in front of the x to get the value of X alone .
2X/2=100/2
The twos cancel out from the X and u divided 100/2 which gives u 50
X=50