Jacob told his son , "My age m years ago was 5 times your age . My age m years hence will be 3 times younger than your age " If the difference of their present age is 40 years , then find the present age of Jacobs son
options
1. 10 years
2. 15 years
3. 9 years
4. 20 years
Answers
Answer:
his age is 9 years...
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Answer:
Present age of Jacob's son is 15 yrs.
Step-by-step explanation:
Let present age of Jacob's son= X yrs
Present age of Jacob= X+40 (as difference of their present age =40yrs)
m Yrs. before,
Age of Jacob's son= X - m yrs.
Age of Jacob= (X+40-m) yrs
By the problem,
5(X-m ) = (X+40-m)
5X-5m=X+40 - m
5X-X= 40-m +5m
4X = 40 +4m_____(1)
After m yrs.
Jacob's sons age = X+m
Jacob's age = (X+40+m)
By the problem,
3(X+m)=X+40+m
3X+3m=X+40+m
3X-X=40+m-3m
2X=40- 2m_____(2)
Multiplying equation (2) by 2 we get,
2×2X=2(40- 2m)
4X=80- 4m_______(3)
From equation (1) and (3) we see that L.H.S is equal so,
40+4m=80 - 4m
4m +4m=80-40
8m =40
m= 40/8=5
Putting the value of m in equation (1) we get,
4X=40+4×5
4X= 40+20
4X=60
X=60/4=15Yrs