Answer:

Step-by-step explanation:
The correct question should be:
We have been told that all we have to do to get profit is to subtract the cost from revenue.
Revenue = 
Cost <em>= </em>
<em />
<em />
Hence:
Profit = 

Putting it in ordered form:

This is an expression for the profit.
Answer:
value of a.b = -4
Step-by-step explanation:
We need to find a.b
a= 4i-4j
b = 4i+5j
We know that i.i =1, j.j=1, i.j =0 and j.i=0
a.b = (4i-4j).(4i+5j)
a.b = 4i(4i+5j)-4j(4i+5j)
a.b = 16i.i +20i.j-16j.i-20j.j
a.b = 16(1) +20(0)-16(0)-20(1)
a.b = 16 +0-0-20
a.b = 16-20
a.b =-4
So, value of a.b = -4
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Answer:
The area of the rectangle is 12 cm² (to two significant figures)
Step-by-step explanation:
To determine the area of a rectangle that is 2.1-cm wide by 5.6-cm long,
The area of a rectangle is given by
Area = l × w
where l is the length
and w is the width
From the question,
l = 5.6 cm
and w = 2.1 cm
Hence, Area of the given rectangle will be
Area = 5.6 cm × 2.1 cm
Area = 11.76 cm²
Now, we will convert the answer to two significant figures
Then,
Area = 12 cm²
Hence, the area of the rectangle is 12 cm² (to two significant figures)
<h2>
Answer: a = ¹/₂ (4 + b)</h2>
<h3>
Step-by-step explanation:</h3>
To solve for 'a' we have to make it the subject of the equation. Since there are two unknowns ('a' & 'b'), we won't get a numerical value of 'a', but an expression in terms of the second unknown 'b'.
Since 2a - b = 4 <em> [add 'b' to both sides]</em>
then 2a = 4 + b <em>[divide both sides by 2 = multiplying by ¹/₂]</em>
a = ¹/₂ (4 + b)