Answer:
j:5j/2+5=45 Or j=16 how you put it was a little confusing
The exponential distribution is:

where

The probability we want is how likely will a dvd player last more than 8 years, given it has already lasted 5 years
To find this, you use conditional probability.

where A is P(x>8) and B is P(x>5)
To find these probabilities, integrate over the distribution:

Sub into conditional probability formula:

Final Answer: Given a dvd player is more than 5 years old, the probability that it will last another 3 more years is about 54.9%
3/k+3=8/k-2
butterfly (multiply 8 and k+3) and (multiply 3 and k-2) and set them = to eachother
8 (k+3)=3 (k-2)
distribute
8k+24=3k-6
-3k both sides
5k+24=-6
-24 both sides
5k=-30
÷5 both sides
k=-6