单项选择题
A child withdraws from his piggy bank 10% of the original sum in the bank. If he must add 90￠ to bring the amount in the bank back up to the original sum, what was the original sum in the bank ？（）
A.$1.00 B.$1.90 C.$8.10 D.$9.00 E.$9.90
单项选择题 The width of a rectangle is 6 cm less than the length. If the perimeter of the rectangle is 48 cm, what is the length of the rectangle in centimeters ？（）
