Question

The points (10,7) and (7,a) fall on a line with a slope of -1/3. What is the value of a?

Answer 1

`a=8`

Explanation:

Slope, has a formula that relates "change in y" over "change in x"

The change in would be from later point to first point, so:

Change in y = a - 7

and

Change in x = 7 - 10 = -3

Now, we can write an equation for slope given as -1/3:

`-(1)/(3)=(a-7)/(-3)`

We can cross multiply and find the value of "a". Shown below is the process:

`-(1)/(3)=(a-7)/(-3)\\3(a-7)=-1*-3\\3a-21=3\\3a=3+21\\3a=24\\a=(24)/(3)\\a=8`

The value of a is 8