substract 17 from both sides
z+17 - 17 < -4 -17
17-17=0
z+0 < -21
z<-21
there will be no change in sign since you are not multiplying or dividng by a negtive number
which can be represented as (- infinity , 21)
note the parenthesis, less than and greater than will use a parenthesis
less than and equal will use a bracket
so will greater than and equal
