Ron’s class donated d dollars to a local charity.
=> Let's use d as an expression of the donation of Ron's class.
Danny’s class donated 21% more than ron’s class.
Let's show this into expression
Expression:
=> 21% / 100% = 0.21
Danny's Class donation=> d + d(.21), where d is the amount of the donation of Ron's class and 0.21 is the 21% of Danny's class