Anybody Know This. ?

Which values for a and b will create infinitely many solutions for this system of equations? ax-y=8 2x+y=b

Which of the following lines is parallel to x=4? a- 3y=9 b- y=4 c- x=2 d- x=y answer this as soon as possible xoxo lo ; )

On the first of each month, shelly runs a 5k race. she keeps track of her times to track her progress. her time in minutes is recorded in the table: jan 40.55 july 35.38 feb 41.51 aug 37.48 mar 42.01 sept 40.87 apr 38.76 oct 48.32 may 36.32 nov 41.59 june 34.28 dec 42.71 determine the difference between the mean of the data, including the outlier and excluding the outlier. round to the hundredths place. 39.98 39.22 0.76 1.21