Question

Reeta was studying in the class 9

thC of St. Surya Public School, Mehrauli, New

Delhi-110030 Once Ranjeet and his daughter Reeta were returning after attending

teachers parent meeting at Reeta's school. As the home of Ranjeet was close to the

school so they were coming by waking.

Reeta asked her father, "Daddy how old are you?"

Ranjeet said, "Sum of ages of both of us is 55 years,After10 years my age will be

double of you. Now you find ages of both of us"

If Ranjeet’s present age is x years and Reeta’s present age is y years, then

i. What is the first equation formed?

a. x - y =55

b. x + y =55

c. x + 2y =55

d. 2x + y =55

ii. What is the second equation formed?

a. x - y =10

b. x + y =10

c. x + 2y = 20

d. x - 2y = 10

iii. If (4, 2) is the solution of 2x+ky=10, then k=

a. 0

b. -1

c. 1

d. 2​

Answer 1

Answer:

i. What is the first equation formed?

b. x + y =55

iii. If (4, 2) is the solution of 2x+ky=10, then k=

k=1

Answer 2

★Given :

• Sum of ages of both Daughter and father is 55 years
• After 10 years,age  of father = Double of Daughter's age.
• Ranjeet’s present age is x years
• Reeta’s present age is y years

★To Find :  

• What is the first equation formed?
• What is the second equation formed?
• If (4, 2) is the solution of 2x+ky=10, then k=?

★Solution :

~To find first equation formed :

Given that,

Sum of ages of both is 55 years.And we have age of ranjeet is x & age of reeta is y.

Therefore,the equation formed will be,

→ x + y = 55

Hence,

Option(B) is correct.

____________

~To find the second equation :

After 10 years,

• Reeta's  age = y + 10  Years
• Ranjeet's  age  =  x+ 10   Years

According to question,

After 10 years,age  of father is Double of Daughter's age.Therefore,

→x + 10 = 2(y + 10)

→x + 10 = 2y + 20

→x - 2y = 10

Hence,

Option(D) is correct.

___________

~To find the value of k :

Given,

• The equation 2x+ky = 10
• Solution of the equation is (4,2)

Therefore,

→x = 4 & y = 2

Substituting the value of x & y in the given equation,

→2x + ky = 10

→2(4) + k(2) = 10

→8 + 2k = 10

→2k = 2

→k = 2/2

→k = 1

Hence,

The value of k is 1.

Option(C) is correct.

_____________