first, the numbers
10 = 2 * 5
5 = 5
14 = 2 * 7
the lcm is 2 * 5 * 7 because 2 * 5 * 7 has 2 * 5 (to make 10), a 5 (to make 5), and 2 * 7 (to make 14)
2 * 5 * 7 = 70
the lcm of 10, 5, and 14 is 70
now the b's
the lcm of b^7, b^5, and b^5 is b^7
note: b^7 = b^5 * b^2
now the a's
the lcm of a^3, a^4, and a^6 is a^6
the lcm of the whole thing is 70(b^7)(a^6)