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 ?()
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 ?()
单项选择题 Two cars left the same town traveling in the same direction. Car A traveled 40 miles per hour and left at 3:20. Car B traveled 50 miles per hour and left at 4:40. At what time will car B catch up with car A ?()