(refer to pic below)

Average speed = 0.09 meter per second.

Step-by-step explanation:

Formula used to find the average speed,

Average speed =

From the graph attached,

Total distance covered from t = 0 and t = 45 seconds

= 4 m

Time elapsed during the journey = 45 - 0 = 45 seconds

Average speed =

                          = 0.09 m per second

Therefore, average speed is 0.09 m per second.

u = -(6/7)w

step-by-step explanation:

place all values with 'u' on one side of the equation.

4u + 8w = - 3u + 2w

4u + 3u = 2w - 8w

further simplify the equation by solving the addition and subtraction.

7u = - 6w

make 'u' the independent variable by placing its co-efficient on the right-hand side.

u = - (6/7)w