Answer: DARN TALL, The answer is 6.125 feet tall
Step-by-step explanation:
Sara is 3 1/2 feet tall, which is equal to 3.5 feet.
Luke is 12 years older than Sara, so he is 12 + 3.5 = 15.5 years old.
Luke is 1 3/4 times taller than Sara, which is equal to 1.75 times her height. Therefore, Luke is 1.75 * 3.5 = 6.125 feet tall.
Therefore, the answer is 6.125.