Question

ratio of age of A and B is 4:5, eight year hence A will be equal to sum of B's age 8 year ago and C's 8 year ago. Average present age of B and C is 30 then present age of C.​

Answer 1

Answer:

age of C is 15

Step-by-step explanation:

let the age of A be a

let the age of B be b

let the age of C be c

given. ratio of a and b is 4:5

i.e) a/b=4/5

5a=4b

a=4b/5. eqn 1

given . a+8=(b-8)+(c-8)

a+8=b-8+c-8

a+8=b+c-8-8

a=b+c-8-8-8

a=b+c-24. eqn 2

given average of b and c is 30.

b+c/2=30

b+c=60. eqn 3

solve eqn 1 and 2

4b/5=b+c-24

4b=(b+c-24)×5

4b= 5b+5c-120

120=5b-4b+5c

120= b+5c

b=120-5c. eqn 4

solve eqn 3 and 4

b+c=60;

120-5c+c=60

120-4c=60

4c=120-60

4c= 60

c=60/4

c=15