John is twice as old as mary. the sum of their ages is 21. how old is mary? let j = john's age and m = mary's age. select the system equations that represents the problem.

The weight of an object in a particular scale is 175.2 lbs. the measured weight may vary from the actual weight by at most 0.1 lbs. what is the range of actual weights of the object

Aword processing program requires a 7- digit registration code made up of the digits 1,2,4,5,6,7 and 9 each number has to be used and no number can be used mor than once how many codes are possible

Pleasseee important quick note: enter your answer and show all the steps that you use to solve this problem in the space provided. use the circle graph shown below to answer the question. a pie chart labeled favorite sports to watch is divided into three portions. football represents 42 percent, baseball represents 33 percent, and soccer represents 25 percent. if 210 people said football was their favorite sport to watch, how many people were surveyed?