Math Help

[creamcheese007]

I can't seem to find the old thread...

The monthly charge for a waste collection service is $12 for 150 kg of waste and is $18 for 180 kg of waste. Find a linear formula for the cost, C, of waste collection as a function of the number of kilograms of waste, w.

Anyone?

[warlock110]

i'm just gonna take a shot here. sorry if it's not too clear, i can't belive i'm having trouble with this haha.
an increase in 30KG = $6
so each KG increase = 6/30 = 1/5

Linear : y=mx +b
Cost = Y
x = Weight

so it'll be something like this

C = 1/5 (x) + b

final solution

C = 1/5 (x) - 18

Plug in some # to test.

12 = 1/5 (150) -18
18 = 1/5 (180) - 18

BTW: i'm able to guess the y int to plug it in, but i've yet been able to find it mathematically, very wierd, let me try n figure it out

Ok i found this on the net
However, you don't know the y-intercept, you know the x-
intercept. The x-intercept is the value of x such that
y = 0. So if you plug in the slope into m, the x-intercept
value into x, and let y = 0, you can solve for b, the
y-intercept.


i guess u just have to guess the x int is (90,0) from graphing, i do not know the way to solve x/y intercept without knowing 1 or the other one. if i knew then i probably forgot

[creamcheese007]

That's the same thing I got. But it's wrong

[creamcheese007]

Wait, nevermine. I did something wrong, I see it now. Sorry, you were right

Thanks

[IcyFox]

What warlock110 did seems to be correct.

Haha random comment.