Question

The weight of a mother and her child together is 70 kg. The weight of the father and the child together is

90 kg. The weight of the father and the mother together is 120 kg. What is the combined weight of the

family?

(A) 100 kg (B) 150 kg

(C) 140 kg (D) 200 kg​

Answer 1

Answer:

hope it will help you.. .. .. .. .. .. .. .. .

Answer 2

The combined weight of the  family is (C) 140kg.

Let the weight of mother be 'm' kg, of child be 'c' kg and father be 'f' kg.

So, the weight of the family = Combined weight of mother, child and father = m + c + f        ...(1)

Given, The weight of a mother and her child together is 70 kg. So,

m + c = 70     ...(2)

Also, The weight of the father and the child together is  90 kg. So,

f + c = 90       ...(3)

c = 90 - f        ...(4)

Replacing the value of c from (4) in (2), we get:

m + 90 - f = 70

⇒ f = 20 + m   ...(5)

Again, the weight of the father and the mother together is 120 kg. So,

f + m = 120      ...(6)

Replacing the value of f from (5) in (6), we get:

20 + m + m = 120

⇒ 2m = 100

⇒ m = 100/2 = 50

So, weight of mother is 50kg.

Putting the value of m in (5), we get:

f = 20 + m = 20 + 50 = 70

So, weight of mother is 70kg.

Putting the value of f in (4),

c = 90 - 70 = 20

So, weight of child is 20kg.

So, the combined weight of family is from (1):

m + c + f = 50 + 20 + 70 = 140 = 140kg.

So, option C is correct.