Answer:
PR = 3.2
Explanation:
We can use proportions to solve this problem. Put the first triangle side over the second triangle side.
BC AC
-------- = ----------
QR PR
Substituting in values
10 8
-------- = ----------
4 PR
Using cross products
10 PR = 8*4
10 PR = 32
Divide by 10
10 PR/10 = 32/10
PR = 3.2