Hi!
In my opinion, the easiest way to solve a problem like this is to find the greatest common factor (GCF) of the numerator and denominator and then divide both numbers by the GCF.
So first we need to find the factors of 45 and 72 and find the factor that has the most value that the two numbers both have.
45: 1, 3, 5, 9, 15, and 45
72: 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72
It looks like the GCF is 9. Now we have to divide 45 and 72 by 9.
45 ÷ 9 = 5
72 ÷ 9 = 8
So the correct answer should be:
[tex] \frac{45}{72} = \frac{5}{8} [/tex]
Hope this helps :)
