Question 197872
What they're asking for is: "How much bigger
is the 2nd pen than the 1st?
So, in words
Difference = (area of 2nd pen) - (area of 1st pen)
{{{A[1] = x*(x+3)}}}
{{{A[2] = (x+5)*(x + 8)}}}
{{{A[2] - A[1] = x^2 + 13x + 40 - x^2 - 3x}}}
{{{A[2] - A[1] = 10x + 40}}}