The diagonals of a square bisect one another and are perpendicular.
so 21x+ 16.5 = 90
subtract 16.5 from each side
21x = 73.5
divide by 21 on each side
21x/21 = 73.5 /21
x = 3.5
About 16 copies cost the same amounts
Answer:
See explanation below
Step-by-step explanation:
The width is 4 inches
So, the area of the base is 20 inches squared
The height is 4 inches
So, the volume of the prism is 80 inches cubed
58.96 or 1887/32 id the answer