6:00 pm - 9¾ hours. ​

Answer is in the photo. I couldn't attach it here, but uploaded it to a file hosting. link below! Good Luck!

cutt.ly/XzW3SUN

The answer should be 9:25 am

Just subtract and use your fingers so you don’t loose track how many you subtracted

This answer uses NMF, which if needed you can read the syntax on my profile:

If we do a partial prime factorisation, we get these, where a and b are the sets containing the prime factors:
a = 10•2 = 20 = {2}^{2}•5
b = 15x{y}^{2} = 3•5•x•{y}^{2}

a∩b = {5}
multiply the elements of a∩b = 5

Therefore the GCF of 10•2 and 15•x•{y}^{2} is 5