2x+5y=619
x=10y-3
________
2(10y-3) +5y=619
20y-6+5y=619
25y=619+6
25y=625
y=625/25
y=25
x=10*25-3
x=250-3
x=247
In order to find which one is or isn't, you need to solve for the value of 'x'.
2x + 15 = 35
2x = 20
x = 10
Substitute x =10, into equation. If each side are not the same (i.e. 0=2), then that's the equation that is not equivalent,
Answer is B
Double check this. Chur! :)
Hope this makes sense.
<u>ANSWER</u>


<u>EXPLANATION</u>
To find the value of a function, f(x) at a given value x=a, we plug in x=a into f(x) to obtain f(a) in simplified form.
The first function is

To find f(7), we substitute x=7, into the function.

The second function is

To find f(4), we replace x with 4 to obtain,


The student had a 40% error estimate