Answer:
See Explanation
Step-by-step explanation:
(a) Proof: Product of two rational numbers
Using direct proofs.
Let the two rational numbers be A and B.
Such that:


The product:




Proved, because 1/3 is rational
(b) Proof: Quotient of a rational number and a non-zero rational number
Using direct proofs.
Let the two rational numbers be A and B.
Such that:


The quotient:

Express as product



Proved, because 3/4 is rational
(c) x + y is rational (missing from the question)
Using direct proofs.
Let x and y be
Such that:


The sum:

Take LCM


Proved, because 7/6 is rational
<em>The above proof works for all values of A, B, x and y; as long as they are rational values</em>
The number ... n
one quarter of the number ... 1/4 of n = 1/4 * n
one third of the number ... 1/3 of n = 1/3 * n
one quarter of the number is subtracted from one third of the number ... 1/3 * n - 1/4 * n
the result is 7 ... = 7
We can put it together:
1/3 * n - 1/4 * n = 7
4/12 * n - 3/12 * n = 7
1/12 * n = 7 /*12
n = 7 * 12
n = 84
The number you are looking for is 84.
Step-by-step explanation:

Answer:
Options A, D and E.
Step-by-step explanation:
Formula to calculate the volume of the triangular prism is,
Volume of the triangular prism = (Area of the triangular base)×(height)
= B × h
Area of the right triangular base = 
= 
= 56 m²
Volume of the prism = 
= 392 cubic meter
Therefore, from the given options correct options are Option A, Option D and Option E.