the complete question is
Edwin graphs the relationship of the gallons of milk he buys in terms of dollars.
Sam buys milk from a different shop. He writes an equation for the amount he spends on milk, p = 3.4g, where p is the cost and g is the gallons of milk bought. Who buys milk at a lower rate, and what is the price?
A) Edwin buys milk at a lower rate, $3.40 per gallon.
B) Edwin buys milk at a lower rate, $3.50 per gallon.
C) Sam buys milk at a lower rate, $3.50 per gallon.
D) Sam buys milk at a lower rate, $3.40 per gallon.
see the attached figure
we know that
1) Sam buys milk at a $3.40 per gallon
step 1
find the equation of the line Edwin's graph
let
A( 0,0) B ( 2,7)
slope m=(7-0)/(2-0)------> m=7/2-----> m=3.5
with m=3.5 and the point A (0,0)
p-p1=m*(g-g1)-------> p-0=3.5*(g-0)-------> p=3.5*g
so
Edwin buys milk at a $3.50 per gallon
$3.40 < $3.50
therefore
the answer is the option
D) Sam buys milk at a lower rate, $3.40 per gallon.
