Question

Find the value of x so that the line passing through (10, 5) and (x, 9) has a slope of -2

Answer 1

slope is \(\frac{9-5}{x-10}\) and you want that to be equal 2, so set
\[\frac{4}{x-10}=2\] and solve for \(x\)

Answer 2

you get
\[\frac{4}{x-10}=2\]
\[4=2(x-10)\]
\[2=x-10\]
\[x=12\]