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)


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 = {{{(- 20)/- 1}}}, or 20 


u = 4(20) ------ Substituting 20 for n in eq (i)


u, or uncle's age = {{{highlight_green(80)}}}


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