Help, me with a math word problem, please?

Question

Ok ,
write the particular equation expressing price in terms of quarts.

Problem:Handy sells one gallon cartons of milk(4 quarts)for $3.09 each and half gallon cartoons for $1.65.Assume that the number of cents you pay for a cartoon of milk varies linearly with the number of quarts the carton holds.

Answer 1

OK, we know the change in price going from 2 quarts to 4 quarts - that is 3.09-1.65=$1.44, so we pay 0.72 per quart.

We know that the equation is linear, so the formula must be
p = A + 0.72q
where p is the price, q is the number of quarts and A is a constant.
We can then plug in a price and number of quarts to work out a value for A:
3.09 = A + 4 x 0.72
3.09 = A + 2.88
0.21 = A

giving us a formula:
p = 0.21 + 0.72q

It is worth checking that this formula works for our other price and number of quarts:
1.65 = 0.21 + 0.72 x 2
1.65 = 1.65
which it does.

Answer 2

3.09/4 = .7725 per quart
1.65/2 = .825 per quart

.825-.7725= .0525 for two quarts difference

.0525/2= .02625

one quart will cost $0.85125 so call it $0.85.

So the formula should be cost = #quarts ($0.85125 per quart) - (#quarts)*($0.02625)

Answer 3

that goes just like this

4quartz( $3.09 ) = (1/2 gallon ) ( $ 1.65 ) k

where k is constant.

this is just a simple analysis in algebra.

Answer 4

pt1...@x=4 .... 3.09 / 4 ... (.7725)
pt2...@x=2 .... 1.65 / 2... (.825)

(y2-y1) / (x2-x1) =slope(.825 - .7725) /(2 - 4)=.1125 / -2=(-.05625)

now ... eq of line is (Y - y1) = m(X - x1)
(Y - .7725) = -(.05625) (X - 4)
(y....) .... -.05625X + .225
Y = -.05625X + ( .225 + .7725)
Y = -.05625X + .9975