Posted by Anonymous on Thursday, December 13, 2012 at 9:13pm.
If the average of these four numbers is 21, find the missing number.
12, 18, 28, ?
What is the missing number and why

Math  Ms. Sue, Thursday, December 13, 2012 at 9:16pm
4 * 21 = 84
12 + 18 + 28 = 58
84  58 = ? 
Math  Anonymous, Thursday, December 13, 2012 at 9:27pm
26!

Math  Ms. Sue, Thursday, December 13, 2012 at 9:36pm
Yes!

Math  Kay, Monday, March 4, 2013 at 3:29pm
12+18+28+x/4=21 58+x=84 x=8458=26

Math  gggggggggggg, Saturday, November 26, 2016 at 6:03pm
26

Math  Owen, Thursday, December 8, 2016 at 5:41pm
26!!!

Math  Anonymous, Thursday, December 15, 2016 at 8:01am
If the average of these four numbers is 21 find the missing number 12,18,28,_,_,_.