Question

weighing the baby at the clinic was a problem. the baby would not keep still and caused the scales to wo wobble. so i held the baby and stepped on the scales while the nurse read off 78kg. then the nurse held the baby while i read off 69 kg. finally, i held the nurse while the baby read off 137kg. what is the combined of all three?
weighing the baby at the clinic was a problem. the baby would not keep still and caused the scales to wo wobble. so i held the baby and stepped on the scales while the nurse read off 78kg. then the nurse held the baby while i read off 69 kg. finally, i held the nurse while the baby read off 137kg. what is the combined of all three?
@Mathematics

Answer 1

You only need to find the baby's weight since you know yours + the nurse's is 137kg.

Set up some simultaneous equations:
let x = you
let y = nurse
let z = baby

x + z = 78
y + z = 69
x + y = 137

Rewrite
x = 78 - z
y = 137 - x
z = 69 - y

Substitution the equations for z and y into the first equation so you can solve for x:

x = 78 - (69 - (137 - x))
x = 78 - (69 - 137 + x)
x = 78 - 69 + 137 - x
2x = 146
x = 73

Find the baby's weight based on the earlier equation:
78 - 73 = 5

Since you know you and the nurse weigh 137kg, just add the baby's weight to get a total of 142 kg.