Which problem can be solved using the equation shown? $2.50x-$2.00=$10.50 a)will bought several books that cost $2.50 each and received a $2.00 discount on his total bill. if he paid $10.50, how many books did he buy? b)will bought several books that cost $2.00 each and received a $2.00 discount on his total bill. if he paid $10.50, how many books did he buy? c) will bought several books that cost $10.50 each and received a $2.00 discount on his total bill. if he paid $2.50, how many books did he buy? d)will bought several books that cost $10.50 each and received a $2.50 discount on his total bill. if he paid $2.50, how many books did he buy?