Answer:
Arlo's weight = 52.3 kg
Explanation:
Let Arlo be "x"
Then,
Arlo = x
Bert = x+20 (Because Bert is 20 heavier than Arlo)
Cassie = x+20-5 (Because Cassie is 5 lighter than Bert)
Donnie = (Because Donnie is half of Bert's weight)
Average = 57
Step by step Calculations:
57 = (The whole divided by 4 because the total people is 4)
57*4 = x + x + 20 + x + 20 - 5 +
228 = 3x + 35 +
228 - 3x - 35 =
193 -3x =
2(193 - 3x) = x + 20
386 - 6x = x + 20
386 - 20 = x + 6x
366 = 7x
x =
x = 52.3 kg (corrected to 3 significant figures)
Therefore Arlo's weight is 52.3 kg