y=kx+b
replace
5=60k+b
10=90k+b
The solution is k = 1/6 and b =-5.
The function expression is: y=(x/6)-5.
2、
Y=0: 0=(x/6)-5。
The solution is x=30.
So users can use 30 megabytes of internet traffic every month.
Coordinates of point C: x=(0+6)/2=3, y=(0+0)/2=0. So c (3 3,0).
The coordinate of the symmetrical point C' of point C about the Y axis is (-3,0).<