Question

Jack is 6 years older than Jill.If four years ago Jack was 3years less than twice Jill'sage, how old is Jill now?

Answer 1

Now:

Jack= 6 + Jill's age (1)

Four years ago:

Jack - 4= (Jill's age - 4)*2 - 3 (2)

We have two equation, both for the Jack's age.

Replacing (1) in the equation (2):

$(6+JillsAge)-4=(JillsAge-4)*2-3$

Solving the equation for Jill's age:

$\begin{gathered} 6+J\imaginaryI llsAge-4=2*J\imaginaryI llsAge-8-3 \\ 6-4+8+3=2*JillsAge-JillsAge \\ JillsAge=6-4+11=13 \end{gathered}$

Answer: Jill is 13 years old now.