First, we need to reduce the equation. To do this, we need to get rid of the parentheses. I'll start with that.
Remember that subtracting 10X-3 is the same as adding a negative number. 10X+(-3) Thus, we change the equation.
10X+(-3)(7-2X)+18
Now we multiply -3 and 7-2X. We must distribute because of the parentheses around 7-2X.
10X+[(-3)(7)+(-3)(-2X)]+18
10X+(-21)+(6X)+18
Now, we add like terms.
10X+6X+(-21)+18
16X+(-3)
16X-3
Now, if you only needed to reduce the equation, then you can stop here.
However, if the equation is equal to zero, and you need to solve for X, then you need to add 3 to both sides so that X is by itself.
16X-3+3=0+3
16X=3
Now decide both signs by 16 to solve for X.
16X/16=3/16
X=3/16
X=0.1875