Let us assume the following letters for respective revenues:
Pen (2006) - A1
Pencil (2006) - B1
Pen (2007) - A2
Pencil (2007) - B2
Now from the given information, we can translate the words into equations as follows:
A2 = \(\frac{105}{100}\) A1 - Equation 1
and
B2 = \(\frac{87}{100}\) B1 - Equation 2
Also, we know that
A2 + B2 = \(\frac{99}{100}\) (A1 + B1) - Equation 3
Now adding equations 1 and 2 together, we get
A2 + B2 = \(\frac{105}{100}\) A1 + \(\frac{87}{100}\) B1 - Equation 4
Equation 3 = Equation 4
So we get,
\(\frac{105}{100}\) A1 + \(\frac{87}{100}\) B1 = \(\frac{99}{100}\) (A1 + B1) = \(\frac{99}{100}\) (A1) + \(\frac{99}{100}\) (B1)
Now, separating the terms we get:
\(\frac{105}{100}\) A1 + \(\frac{87}{100}\) B1 = \(\frac{99}{100}\) (A1) + \(\frac{99}{100}\) (B1)
Rearranging terms and canceling the denominator 100 on both sides, we get
(99-87) B1 = (105-99) A1
So \(\frac{B1}{A1}\) = \(\frac{105-99}{99-87}\) = \(\frac{6}{12}\) = \(\frac{1}{2}\)
Is this answer right?