Final answer:
To find the ratio of Sarah's age to Keisha's age 9 years from now, determine their ages in the current year and calculate their ages 9 years from now, expressing the ratio as a result.
Step-by-step explanation:
To find the ratio of Sarah's age to Keisha's age 9 years from now, we need to determine their ages in the current year. Let's assume that Sarah is 4x years old and Keisha is 5x years old this year. We are given that Keisha was 12 years old 3 years ago, so we can set up the equation 5x - 3 = 12 and solve for x. Once we find the value of x, we can calculate Sarah's age 9 years from now by multiplying 4x by 9 and Keisha's age 9 years from now by multiplying 5x by 9. Finally, we can express the ratio of Sarah's age to Keisha's age 9 years from now as 36x : 45x.