It is not possible to give a sensible answer to this question. The least common multiple (LCM) refers to a multiple that is COMMON to two or more numbers (or expressions). You have only one expression in the question: 15xy.
Also, if 5x3y is different from 15xy then multiplication is not commutative in whatever set these belong to. In that case it is impossible to find the LCM without information about the rules of "multiplication" in this set.
GCF(18xy, 15xy) = 3xy LCM(18xy, 15xy) = 90xy
30xy
60xy
153m3n6
80a^3
You need at least two terms to find an LCM.
10x2 - 20xz + 15xy = 5x (2x - 4z + 3y)
The LCM of 3s and s^2 is 3s^2
35
Monomial. Monomial. Monomial. Monomial.
15xy-2xy-7x+x=13xy-6x
15y