Answer:
Step-by-step explanation:
first we gotta find the slope of the first line
(-4,-3),(4,1)
slope = (y2 - y1) / (x2 - x1) = (1- (-3) / (4 - (-4) = (1 + 3) / (4 + 4) = 4/8 = 1/2
so the slope is 1/2.....so we are looking for a line that is perpendicular....perpendicular lines have negative reciprocal slopes...all that means is flip the slope and change the sign....so the slope we need is :
1/2....flip it....2/1.....change the sign....-2.....we need a -2 slope
y - y1 = m(x - x1)
slope = -2
(-4,3)...x1 = -4 and y1 = 3
now sub
y - 3 = -2(x - (-4) =
y - 3 = -2(x + 4) <=====
These two lines have the same rate of change
Call the notebooks x, and the pencils y.
<span>3x + 4y = $8.50 and 5x + 8y = $14.50 </span>
<span>Then just solve as simultaneous equations: </span>
<span>3x + 4y = $8.50 </span>
<span>5x + 8y = $14.50 </span>
<span>5(3x + 4y = 8.5) </span>
<span>3(5x + 8y = 14.5) </span>
<span>15x + 20y = 42.5 </span>
<span>15x + 24y = 43.5 </span>
<span>Think: DASS (Different Add, Similar Subtract). 15x appears in both equations so subtract one equation from the other. Eassier to subtract (15x + 20y = 42.5) from (15x + 24y = 43.5) </span>
<span>(15x + 24y = 43.5) - (15x + 20y = 42.5) = (4y = 1) which means y = 0.25. </span>
<span>Then substitue into equation : </span>
<span>15x + 20y = 42.5 </span>
<span>15x + 5 + 42.5 </span>
<span>15x = 42.5 - 5 = 37.5 </span>
<span>15x = 37.5 </span>
<span>x = 2.5 </span>
<span>15x + 24y = 43.5 </span>
<span>15(2.5) + 24(0.25) </span>
<span>37.5 + 6 = 43.5 </span>
<span>So x (notebooks) are 2.5 ($2.50) each and y (pencils) are 0.25 ($0.25) each.</span>
I think it’s D because the definite can’t be a negative
