Question

How do you simplify the ratio 20:5

Answer 1

because both numbers are divisible by 5 you can just do:
20/5=4
5/5=1

the new ratio is 4:1

Answer 2

take factors of 20 and 5. so for 20 you'd have: 1, 2, 4, 5, 10, 20. factors of 5 are 1,5. both of these numbers are divisible by 5 so divide them each by that number and your answer is 4:1