Divide the sum of 3/8 and -5/12 by the reciprocal of -15/8×16/27

Molly shared a spool of ribbon with 12 people. each person received 3 feet of ribbon. which equation can she use to find r, the number of feet of ribbon that her spool originally had?

Aclassmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.

Zack and tia played chess for 50 min they put the chessboard away at 11: 20 when did they start