Hi !
So,here we have to calculate the least common multiple of the numbers 15,25,9,8.
We have to break down every number as a prime number product:
15 = 3·525 = 5² 9 = 3² 8 = 2³
Then,we have to select common and uncommon numbers at the highest power so:
lcm : 2³·3²·5² = 8·9·25 = 1800