Answer:
15:2
Step-by-step explanation:
The GCD of 3000 and 400 is 100, so your first step would be to divide both numbers by 100, giving you 30/4.
Their GCD is 2, so divide both numbers by 2.
30/2 = 15, 4/2 = 2.
Therefore, the ratio in its simplest form is 15:2.