22. Yura left the house for school 5 minutes later than Lena, but walked twice as fast as she did. How many minutes after leaving will Yura catch up to Lena?
22. If Lena walks $a$ m in 1 min, then Yura walks $2a$ m. Let him catch up with her after $x$ min from his start. Then we have $a \cdot 5 + a \cdot x = 2a \cdot x$, from which $x=5$.