5x+3x=420 12x+9=1080 What does x and y equal?

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

2x minus y equals 6, x plus y equals negative 3

Mis the midpoint of rq if rm equals 2x + 5 and mq equals 4x - 9 what is the length of rq