Answer:
The line AB, with A(Ax, Ay), B(Bx, By) and midpoint M(Mx, My) satisfying:
Ax + Bx = 2Mx
Ay + By = 2My
=>
2 + Bx = 2*1
5 + By = 2*2
=> Bx = 0
=> By = -1
=> B(0, -1)
Hope this helps!
:)
Answer: The correr solution is 
Step-by-step explanation:
Since the steps in Lin's solution are not shown, we are not able to find her erros. However, we can solve it step by step and find the correct result:
Firstly, in the left part of the equation we have to multiply 
by the numbers inside the parenthesis; and in the right side we have to solve first what is inside the parenthesis:
Adding similar terms in the left side and multiplying 
by the number inside the parenthesis in the right side:
Isolating 
:
This is the correct solution
Answer:
53 1/3 km/h
Step-by-step explanation:
average speed = (total distance)/(total time)
average speed = distance/time
time * average speed = distance
time = distance/(average speed)
250 km at 75 km/h
distance = 250 km
time = (250 km)/(75 km/h) = 3.33333... hours
350 km at 70 km/h
distance = 350 km
time = (350 km)/(70 km/h) = 5 hours
200 km at 30 km/h
distance = 200 km
time = (200 km)/(30 km/h) = 6.6666... hour
total distance = 250 km + 350 km + 200 km = 800 km
total time = 3.33333... hours + 5 hours + 6.66666... hours = 15 hours
average speed = (total distance)/(total time)
average speed = (800 km)/(15 hours)
average speed = 53 1/3 km/h
