This is a linear expression, so generally it will have 1 solution, but it could have no answers or infinitely many answers. Simplify the expression and solve for x.
3x+9-6x(6+8)=7(7+3)
Simplify the expressions in the brackets.
3x+9-6x(14)=7(10)
Complete the multiplications.
3x+9-84x=70
Move every term that has the variable in question (x) to the left and all other terms to the right. Remember to switch signs when you switch sides.
3x-84x = 70 - 9
Simplify each side.
-81x = 61
Divide each side by -81.
x = -61/81
There is one solution to this equation.
If the result had been something like:
0=0
then there would have been an infinite number of answers. It would have meant that for any value of x, you had a true answer.
If the results had been something like:
0=1
then there would have been no solutions. No matter what value you set for x, it will never work out.