Are the following equations equivalent? explain your reasoning. x-5=12 and 12=x-5

Yes, they are equivalent. These two equations are just reversed by still have the same value. This is basically the commutative property in which you can move around the numbers but still get the same answer. 

x-5=12                                         12=x-5
get the x by itself.                        get the x by itself.
x-5=12                                         12=x-5
  +5  +5                                        +5    +5
x=17                                             x=17

Hope this helps! If you have any questions, ask me!