Simplify both sides of the equation
3x+1/10 = x+ -1/7
Subtract x from both sides
3x+1/10 -x = x+ -1/7 -x
2x+1/10 = -1/7
Subtract 1/10 from both sides
2x+1/10 - 1/10 = -1/7 -1/10
2x= -17/70
Divide both sides by 2
2x/2 = -17/70/2
x= -17/140
decimal x will equal -0.121
Ask any questions you want and I hope that's help !