My number is a multiple 5. it is less than 100 and has a factor of 6. what is my number

If it is a multuple of 5 and a factor of 6, find their lcm

5 and 6 have no common factors except 1
so the lcm is 30

so any multipule of 30 will be a multipule of 5 and have a factor of 6

30 times 1=30
30 times 2=60
30 times 3=90
30 times 3=120,oops, over 100

so your number could be 30 or 60 or 90