9514 1404 393
Answer:
 (a)  8 km
Step-by-step explanation:
Let m represent the distance (in kilometers) Michelle has walked. Then Janet walked a distance of (m-2). These distances are at right angles, so the distance between them can be found using the Pythagorean theorem.
 m² +(m -2)² = 10²
 m² +m² -4m +4 = 100
 2m² -4m = 96 . . . . . . subtract 4, collect terms
 m² -2m +1 = 49 . . . . . divide by 2 and add 1
 (m -1)² = 7² . . . . . . .write as squares
 m -1 = 7 . . . . . . positive square root
 m = 8
Michelle walked 8 km.