Question

the point (a,3) lies on the graph of the equation 5x + y = 8, then a=

Answer 1

Ok, so in an ordered pair the numbers are the values for (x,y). That means if you plug in the number in y's place, you will get the number that is in x's place.

Answer 2

Your equation is 5x+y=8, and your pair is (a,3).
Since we know that the 3 is our y value, we can plug 3 in for y to find a.

5x+3=8
Then subtract 3 from both sides
5x=5
Now divide by 5
X=1
So, when y=3, x=1.

Since we know that a is the x value, a=1