Answer:
the answer is 96 squared feet
We know
90
∘
=
1
right angle
=
100
g
So
A
∘
=
(
100
90
⋅
A
)
g
Hence by the given condition
B
=
(
100
90
⋅
A
)
=
10
9
A
=
A
+
(
A
9
)
Answer
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>
