Question

Jessica is 5 years older than her sister Jenna. Jenna tells her sister that in 5 years, she will be as old as Jessica was 5 years ago. If Jenna’s age is x, which equation represents the situation? How many solutions does the equation have?

Answer 1

Jenna's age Jessica's age

today x x + 5


in 5 years x+5

5 years ago. X-5 x-5


Equality x + 5 = x + 5 - 5

=> x + 5 = x


The equation is x + 5 = x


That equation has not any solution, because it reduces to 5 = 0, which is an absurd.


So, the conclusion is that information given by Jenna is wrong.


It is logical: if the difference of the ages is 5, in five years Jenna will have 10 years more than what her sister had 5 years ago, no 5 as she told Jessica.