問數條中2數學

a) 45minutes = 0.75hour
　0.75X 0.75Y = 60

b) 3X-60 = 3Y

c) 0.75X 0.75Y = 60
　X Y = 80......(1)
　3X-60 = 3Y
　X - Y = 20......(2)
(1) (2), 2X=100
　　　　X=50
　　　　Y=30

2) Let n be the number of sides of the polygon.
　180(n-2) = 7(360)
　180n -360 = 7(360)
　180n = 8(360)
　n = 8(2)
　n=16
The number of sides of the polygon is 16.

雖然002答得好細,但係太多野...會令到睇既人好唔舒服

1.Car X and Car Y are 60km apart on a highway and they travel at a constant speed of X km/h and Y km/h respectively.



a.If Car X and Car Y travel towards each other, they will meet after 45 minutes. Writhe down an equation connecting X and Y.



b.If Car X and Car Y travel towards the same direction, Car X will catch up with Car Y after 3hours. Writhe down an equation connecting X and Y.



c.Hence,find the values of X and Y.



2.If the sun of all interior angles of a polygon is 7 times the sum of its exterior angles, find the number of sides of the polygon

1a) 0.75X + 0.75Y = 60

1b) 3X = 3Y + 60

1c) X = 50km/h ; Y = 30km/h