Please help me with these 6 questions Ill give brainliest to whoever answers them all correct or whoever answers them and just gets 1 wrong (ill add the last question in my next post so u can answer it)

Simplify -4z+2y-y+-18z a.-22z+y b.-14z+2 c.3y+22z d.y +14z

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.

Ur environment is very sensitive to the amount of ozone in the upper atmosphere. the level of ozone normally found is 4.04.0 parts/million (ppm). a researcher believes that the current ozone level is not at a normal level. the mean of 2525 samples is 4.44.4 ppm with a standard deviation of 0.80.8. assume the population is normally distributed. a level of significance of 0.020.02 will be used. make the decision to reject or fail to reject the null hypothesis. answer tables