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?

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

point a is the center of the circle that passes through points e, f, and g and the center of the circle that passes through points x, y, and z.