We have two numbers say a, b. And a system of equations.

It looks a bit intimidating but it's actually very easy.
Instead of term a + b in the second equation we can say it's zero because the first equation describes a + b as being equal to 0.
So,

The above equation is not true therefore numbers a and b do not exists in the real number domain.

No solution.
Hope this helps.
A is the correct answer. PEMDAS for single step and double step equations alike.
The chance that one of the defective components is

or 2.14285714% that the qc person will test a defective unit.
-10x. All you have to do is subtract -2 from -8 and then put an x there so it’s -10x
Negative square root of 25 is -5
Negative square root of 100 is -10