1. The probability that your mail is delivered before 2 pm is 0.9, so the probability that the mail is delivered at 2 pm or after 2 pm (so not before 2 pm) is 1-0.9=0.1.
Remark: 0.9=9/10=90/100=90%, and 0.1 is 10%
2. Probability of the mail being delivered before 2 pm for 2 consecutive days is

3. take a look at the picture attached, the tree diagram is another method we could use.
In step 2 .. because when you multiple by -4 in step 1 , the equation in step 2 will be ( -4y =-16 + 8z)
Is there supposed to be a picture here?? There isn’t.
Answer:
<5 ~= <1 - Corresponding Angles Theorem
<1 ~= <7 - Alternate Exterior Angles Theorem
<5~= <7 - Vertical Angles Theorem
line l || line m - Transitive Property
2x6=12
3x6=18
12+18=22
2x3=6
2x6=12
6+12=18