Pls help. do all three for brainliest!
2 answers:
Answer:
720 cm³
Step-by-step explanation:
Rectangular pyramid:
Volume =
H = 9 cm
B-> base area = area of rectangle
B = length * width = 8*9 = 72 square cm
Rectangular prism:
length = l = 8 cm
Width = w = 9 cm
Height = h = 7 cm
Volume of rectangular prism = l * w * h = 8 * 9 * 7 = 504 cm³
Volume of composite figure = volume of pyramid + volume of r. prism
= 216 + 504
= 720 cm³
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Answer:
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Explanation:
r = number of red pens
4r = cost of buying r red pens
example: if r = 10, then 4r = 4*10 = 40 is the total cost of buying 10 red pens
If John buys r red pens, then he must buy 20-r black pens so that r and 20-r add to 20.
John buys 20-r black pens, and at $5 each, so it will cost 5(20-r) dollars for just the black pens alone.
In total, John spends 4r + 5(20-r) dollars for all the pens (red & black)
We want $92 be the most he spends. This is the ceiling or highest value possible.
Therefore,
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Extra info:
If you want to solve for r, then
distribute
add r to both sides
subtract 92 from both sides
So John must buy at least 8 red pens. The most he can buy is 20 red pens since he wants 20 pens total.