Answer:
90.
Step-by-step explanation:
Here 5 is one of the 4 prime factors, so dividing the lower (80) and upper limit (100) by 5 we have new lower limit 16 and new upper limit 20.
So the product of other 3 factors should be greater than 16 and less than 20. And we can have it from 18 only. Hence the number is 90.
The numbers between 80 and 100 having factor 5 are
80, 85, 90, 95, 100
16 = [tex]2^{4}[/tex]
17 = 17
18 = 2× 3 × 3
19 = 19
20 = [tex]2^{2}[/tex] × 5
90 = 2 × [tex]3^{2}[/tex] × 5
