-3+m/9=10
Add 3 to both sides:
m/9 = 13
Multiply both sides by 9:
m = 13 * 9
m = 117
I really think it's 4 or B
There is more than one solution because there are two different numbers whose square is 9. One of them is +3. The other is -3.
The fundamental theorem of algebra says every non-zero single-variable polynomial of degree N has exactly N roots, counting multiplicity. Your polynomial is degree 2, so has 2 roots.