First will fail is 1-3/5=2/5

Second will fail is 1-4/7=3/7

Thus, we multiply the probabilities,

(2/5)(3/7)=6/35

2 possibilities...then i need the probability that only one will pass

1)First person fails and second person passes.

2)First person passes and first person fails.

The probability in #1 is:

(2/5)(4/7)=8/35

The probability in #2 is:

(3/5)(3/7)=9/35

This is an OR question. Meaning #1 OR #2 thus we add,

8/35+9/35=17/35