Ann purchased a prepaid phone card for 20$. Long-distance calls cost 12 cents a minute using this card. Ann used her card only once to make a long-distance call. If the remaining credit on her card is 16.76$, how many minutes did her call last?

You have two cards with a sum of -12 in both hands. a. what two cards could you have? b. you add two more cards to your hand, but the total sum if the cards remains the same, (-12).

The number of revolutions of two pulleys is inversely proportional to their diameters. if a 24-inch diameter pulley making 400 revolutions per minute is belted to an 8-inch diameter pulley, find the number of revolutions per minute of the smaller pulley.

Hiroaki wants to find 3 3/4 - 7/8 explain why he must rename 3 3/4 to do the subtraction.