Question 535335: a man when asked by his niece how old he was, he replied, My age is now 4x yours, but 5yrs ago it was 5x yours. (he is 80 but how do you solve it)
uncle's age = u , niece's age = n
u = 4n ...(i)
u-5 = 5(n-5) ...(ii)
Found 4 solutions by fcabanski, josmiceli, amalialaila, MathTherapy:
Answer by fcabanski(1391)   (Show Source):
You can put this solution on YOUR website! Check my profile and contact me for one on one online tutoring.
Y = Man's age
X = neice's age
Currently y = 4x
5 years ago y-5 = 5 (x-5) Five years ago the man was y-5 years old, current age - 5. Neice was x-5 years old, current age - 5. And the man (y-5) was 5 times older than the neice 5*(x-5).
Substitute the value of y, in terms of x, from the first equation into the second. Then solve for x.
4x-5=5(x-5) ---> 4x-5=5x-25 (subtract 4x from both sides, add 25 to both sides.
20=x. Remember the man is currently 4x old, and 4(20)=80.
Answer by josmiceli(19441)  (Show Source):
Answer by amalialaila(3) (Show Source):
You can put this solution on YOUR website! substitute equation (i) to (ii)
4n-5 = 5(n-5)
4n-5 = 5n-25
4n-5n= -25+5
-n = -20 --> multiply -1
n = 20
substitute the niece's age to equation(i): u=4n, and we will get that uncle's age was 80, as told.
u = 4n
u = 4(20)
u = 80
Answer by MathTherapy(10552)  (Show Source):
You can put this solution on YOUR website!
a man when asked by his niece how old he was, he replied, My age is now 4x yours, but 5yrs ago it was 5x yours. (he is 80 but how do you solve it)
uncle's age = u , niece's age = n
u = 4n ...(i)
u-5 = 5(n-5) ...(ii)
Good job creating the equations, but you need to expand on eq (ii)
u = 4n ...(i)
u-5 = 5(n-5) ...u - 5 = 5n - 25 ...... u - 5n = - 20 ------ (ii)
Now, since u = 4n [eq (i)], we can substitute this value for u in eq (ii), as follows:
4n - 5n = - 20
- n = - 20
n, or niece's age =  , or 20
u = 4(20) ------ Substituting 20 for n in eq (i)
u, or uncle's age = 
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