Part a: the first cereal is y=12x and the second one is y=8x so they are $4 apart.
part b: y=12*4 and y=8*4 is $16 apart so she will save $16 each month.
The topsoil will be 4.05 inches deep
<h3>Calculating depth</h3>
From the question, we are to determine how many inches deep the topsoil will be
From the given information,
The volume of the topsoil = 1 cubic yard
Convert to cubic feet
1 cubic yard = 27 cubic feet
∴ The volume of the topsoil = 27 cubic feet
Then,
The depth of the topsoil will be = 27/(8 ×10)
Depth of topsoil = 27/80
Depth of topsoil = 0.3375 foot
Now, convert to inches
1 foot = 12 inches
∴ 0.3375 foot = 0.3375×12 inches
= 4.05 inches
Hence, the topsoil will be 4.05 inches deep
Learn more on Calculating depth here: brainly.com/question/15489457
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Rounded to the nearest tenth is 4
The answer would be D because V= side length times 3