Kim is twice the age of Ryan. In 4 years Kim will be 7 years older than Ryan. How old is Kim now?

Answer 1

K=2R.....(1)
K=R+7 ....(2)
She is always 7 years older than Ryan, now or in 4 years.
Solve for K.

If you rewrite (1) as
K=R + R
and compare with (2), you will solve for R mentally.