T = 60
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Answer:
Step-by-step explanation:
- Speed in one direction = 40 km/h
- Speed on return = x
- Average speed = 60 km/h
Let the distance be d
<u>Average speed </u>
- 2d/(d/40 + d/x) = 60
- d/40 + d/x = 2d/60
- 1/40 + 1/x = 1/30
- 1/x = 1/30 - 1/40
- 1/x = (4-3)/120
- 1/x = 1/120
- x = 120 km/h
B a counterclockwise rotation about the origin of 90°
under a counterclockwise rotation about the origin
a point ( x , y ) → (- y, x)
figure Q to figure Q'
( 4,2 ) → (- 2, 4 )
(7, 5 ) → (- 5, 7 )
(3, 7 ) → (- 7 , 3 )
(2, 4 ) → (- 4, 2 )
(5, 4 ) → (- 4, 5 )
the coordinates of the original points of the vertices of Q map to the corresponding points on the image Q'