Mass question

Question

john is 1 1/3 times as heavy as Mary. If their total mass is 112 kg, find the mass of john.

Answer 1

john is 1 1/3 times as heavy as Mary.

 

1 and 1/3 is equal to 4/3

3/3 + 1/3 = 4/3

 

So John is 4/3 Mary's mass

Let's make Mary's mass = x

Then John's mass = 4x/3

 

If their total mass is 112 kg, find the mass of john.

 

x + 4x/3 = 112

 

(one can be written as 3/3 to get a common denominator)

 

3x/3 + 4x/3 = 112

 

7x/3 = 112

 

7x = 112*3

 

7x = 336

 

x = 336/7

 

x = 48

 

Mary's mass is 48 kg

 

If their masses combine to make 112 kg then; Mary + John = 112

 

john + 48 = 112

 

john = 112 - 48

 

john = 64 kg

Answer 2

Let the mass of Mary = x

 

John has a mass of 1 1/3 * x = (4/3)x

 

x + (4/3)x = 112

 

(7/3)x = 112

 

Multiply both sides of the equation by 3

 

7x = 336

 

x = 48

 

Mary has a mass of 48 kg, and John has a mass of (4/3) * 48 = 64 kg