2c+1_d-5d+c= 3c+ 6d 4b-8d+2b= _b-8a
21k- _k +k= 15k
_m +n - 4m+ _n= 5m +4n
18r-3s-_r+4s= 1_r+s
_x +4.9y+ 1.7 * 8.2* + 4.9y
_c-2.1c-3c* 0.3c
Fill in the blanks
PLEASE HELP IF I DONT FINISH THIS I WONT HAVE MY COMPUTER AND PHONE FOR A MONTH!!

According to statistics a person will devote 32 years to sleeping and watching tv. the number of years sleeping will exceed the number of years watching tv by 18. over a lifetime, how many years will the person spend on each of these activities

What is the standard deviation of the following data set rounded to the nearest tenth? 3, 17, 18, 15, 12, 21, 9

Icould really use some with this question.