Question 1 What is the GCF of 15, 20, 30?

-- Answer -- 5

15 = 3 * 5, 20 = 2 * 2 * 5, 30 = 3 * 2 * 5 => 5

Question 2 What is GCF of the expression: x² * y⁴ * z + z² * 2x * y³?

-- Answer -- xy²z

x² * y⁴ * z = x * x * y * y * y * y * z

z² * 2x * y³ = z * z * x * y * y * y => x * y² * z

Question 3 The GCF of 2 numbers is 15. The LCM is 90. What are the numbers (20&30, 30&45, 45&60)?

-- Answer -- 3*3*2*5

30, 45 – 3*5*2 & 3*3*5 = 3*3*2*5