Ok, so
We know that 85 cars had defects
Then, the probability to produce one car with defects will be:
P = 85/5,000 (which is equal to 0.017.)
We want to know how many cars can be expected to have defects for a total of 100,000.
For this, we multiply:
0.017 * 100,000, and this is 1700 cars.