Answer:
A. Subtract x from both sides: (i.e. 5+x-12 = x-7 <--> 5-12 = -7)
This equation is identically true, so it holds no matter what x is.
B. This one is pretty self-explanatory
Step-by-step explanation:
u wrote the question wrongly the answer is in answer box
This question also my teacher gives me
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This expression is already simplified.
X+1 Hours, because Zavier begins work an hour earlier than Abigail.
Answer:

Step-by-step explanation:
Let's re-write the equations in order to get the variables as separated in independent terms as possible \:
First equation:

Second equation:

Third equation:

Now let's subtract term by term the reduced equation 3 from the reduced equation 1 in order to eliminate the term that contains "y":

Combine this last expression term by term with the reduced equation 2, and solve for "x" :

Now we use this value for "x" back in equation 1 to solve for "y":

And finally we solve for the third unknown "z":
