When Famke charges her phone, it gains 222 percentage points each minute. When Famke uses her phone, it loses 555 percentage points each minute. Once, Famke used her phone for some time, and then charged it for twice the amount of time she used it. In the end, her phone lost 101010 percentage points. How long did Famke use her phone and how long did she charge it?

To answer this you can use a guess and check strategy.

Start with 5 minutes using it (25% lost) and 10 minutes charging (20% gained).

Try 7 minutes using it (35% lost) and 14 minutes charging (28%).

Next, 9 minutes (45%) and 18 minutes(36%).

10 minutes (50%) and 20 minutes (40%). This is the difference.

She used it for 10 minutes and charged it for 20 minutes.