Question

Rearranging formula

18
4 friends weigh themselves. Bert is 20kg heavier then Arlo. Cassie is 5 kg lighter then Bert and Donnie is half of Berts weight. If their average weight is 57kg how much does Arlo weigh?

Answer 1

Arlo's weight = 52.3 kg

Step-by-step 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 =
`(x+20)/(2)` (Because Donnie is half of Bert's weight)

Average = 57

Step by step Calculations:

57 =
`((x) + (x+20) + (x+20-5) + ((x+20)/(2) ))/(4)` (The whole divided by 4 because the total people is 4)

57*4 = x + x + 20 + x + 20 - 5 +
`(x+20)/(2)`

228 = 3x + 35 +
`(x+20)/(2)`

228 - 3x - 35 =
`(x+20)/(2)`

193 -3x =
`(x+20)/(2)`

2(193 - 3x) = x + 20

386 - 6x = x + 20

386 - 20 = x + 6x

366 = 7x

x =
`(366)/(7)`

x = 52.3 kg (corrected to 3 significant figures)

Therefore Arlo's weight is 52.3 kg