How to solve 3 = 10 - n

Question

I don't know how to do this at all. Please help 

Answer 1

3 = 10 - n

-7 = -n          subtract 10 from both sides

7 = n            multiply both sides by -1

 

or

 

3 = 10 - n

3 + n = 10      add n to both sides

n = 7              subtract 3 from both sides