Please help me with question 5 and 6.

While walking home, you notice that you still need to travel 7 km east then 3 km south. Wanting to get home as quickly as possible, you realize that part way into the 7 km walk, you can cut across a field to for a more direct route home. You decide to run part of the way, with a speed of 6.5 m/s then walk the rest of the way at a speed of 3.4 m/s. How far along the 7 km distance should you run before turning to cut through the field so you reach home as quickly as possible? you 7 km .mTH walkb' 3 km 6. A box with an open top is to be constructed from a square piece of cardboard, 6 m wide, by cutting out a square from each ofthe four corners and bending up the sides. Find the largest volume that this box can have