Question

Mary draws the number line below to repersent the solution set of the inequality 50-8t<90

Answer 1

50-8t<90 
50-90<8t
-40<8t
8t>-40
t>-5
Solutions should go to the right.
Mary probably was solving it as following
50-8t<90 
-8t<90-50
-8t<40  (here, when she divided both sides by -8, she had to change sign <  to the sign >)
But she did not change the sign, and got
t<-5