the four consecutive natural numbers which are multiple of five can be written as

5x - 5, 5x, 5x + 5, 5x + 10

where x is integer

the product of the numbers is 15000

(5x - 5)5x(5x + 5)(5x + 10) = 15000

(5^4)(x - 1)x(x + 1)(x + 2) = 15000 divide both sides by 5^4

(x - 1)x(x + 1)(x + 2) = 24

24 = 1*2*3*4

thus an integer solution if x = 2 since

(2 -1)*2(2 + 1)(2 + 2) = 24

the numbers are

5*2 - 5 = 5

5 + 5 = 10

10 + 5 = 15

15 + 5 = 20

indeed

5*10*15*20 = 15000

the numbers are 5, 10, 15 and 20.