Since you know the sides are equal you can make an equation setting them equal to each other:
4x+18=10x
Now we solve. We want all the ones with x values on one side so we move the 4x to the right side by subtracting 4x from both sides.
18-4x+4x=10x-4x
18=6x
Now, we can divide both sides by 6 to get the value of x
18/6=6x/6
3=x
I hope that helps.