<u>Answer:</u>
96
<u>Step-by-step explanation:</u>
Let's assume that the marks needed in the next exam is
. Then if the average becomes 90,

Now we can simply solve for
:
⇒ 
⇒
[Multiplying both sides by 4]
⇒
[Subtracting 264 from both sides]
⇒ 
Therefore, you need to score 96 in your next exam to have an average of 90 on the four exams.
Answer:
n<7
Step-by-step explanation:
hope i did okay for you
The reason why the trails must be in quadrant 2 or 3 is because the coordinates start with a negative number. Quadrant 2= (-,+) and quadrant 3= (-,-)
Since she has seven key the probability that the first one will open the door is

if it takes three attempts to open the door,the probability is

if the three attempts would not work
then the probability that the fourth attempt will open the door is

hope this helps
Answer:
53
Step-by-step explanation:
20-5y+2x
20-5(-3)+2(9)
20--15+18
cancel out the negative signs
20+15+18
=53