Question

The total mass of Alice and Bernice is 90.45 kg. The total mass of Alice and Mei Ling is 61.2 kg. Bernice is 4 times as heavy as Mei Ling. What is Alice's mass?

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Answer 1

Explanation:

a = Alice

b = Bernice

m = Mei Ling

a + b = 90.45

a + m = 61.2

a = 61.2 - m

b = 4m

so, we bring the last 2 equations into the first :

61.2 - m + 4m = 90.45

61.2 + 3m = 90.45

3m = 29.25

m = 9.75 kg

a = 61.2 - m = 61.2 - 9.75 = 51.45 kg

b = 4m = 4×9.75 = 39 kg

Alice's mass is 51.45 kg.