MATH HELP - Algebraic Reasoning?

Question

Ignatius Trott had, at the age of 7 years, a Conscience able to support a weight of 27 lb., 4 oz. The weight which it could carry increased every year thereafter 18 lb., 7 oz. What weight (in lb) can his Conscience support at his present age, 

57 1/2 years?" (If you have forgotten, 1 pound or 1 lb = 16 ounces or 16 oz. Advice: Work with fractions. Assume the weight increases continually throughout the year. Enter your answer using mixed units. Enter less than 16 oz.)

Answer 1

27 lb 4 oz = 436 oz

18 lb 7 oz = 295 oz

years = 57.5 - 7 = 50.5

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w = 436 + 295(50.5)

w = 15,333.5 oz

w = 958.34375 lb

w = 958 lb 5½ oz <––––––