√z = 13 - 8
√z = 5
z = 5²
z = 25
In this case the z can be any number, however z cannot be less than 0 and that is the restriction. (for example; √-1 = irrational number, cannot be solved.)
For this case we have the following system of equations:

To solve, we clear "x" from the second equation:

We substitute "x" in the first equation:

We clear the value of the variable "y":

We look for the value of the variable "x":

Thus, the solution of the system is given by:

Answer:

Option D
14.5% = 0.145 = 145/1000
14.5 = 14500/1000
<span>So 14.5% is a hundredth the size of 14.5, so they are not equal and the friend is incorrect.</span>