First u gone have too find the prime factorization of 14 and Thts 14 = 2 x 7
Second u gotta find the prime factorization of 18 and Thts gone be 18 = 2 x 3 x 3 and third u gone multiply each factor and the greater number of times it occurs in steps to find the LCM , you gone do LCM = 2 x 3 x 3 x 7, LCM = 126