#### Answer

GCF = 15

#### Work Step by Step

To find the GCF, write each number as a product of primes:
45 = (3)(3)(5)
60 = (2)(3)(2)(5)
To find the GCF, identify the common prime factors. Each number has a common prime factor of 5 and 3. The GCF is the product of these common prime factors.
3 x 5 = 15
15 is therefore the biggest number that goes both into 45 and 60.