Answer:
His claim is wrong as the percent increase is 21%.
Explanation:
The given expression is:
Given is that at the time of purchase, the house it was valued at 'd' dollars.
So, original price (d) plus percent increase on original price (0.21d) equals to current price (1.21d)
We can see that the percent increase was 21%.
Mr. Porter claims that the value of his house has increased by 121%, since 1.21 is equal to 121%.
His claim is wrong as the percent increase is 21%.