15 * 15 * 15 * 500 = 1,687,500. it's different from finding 45 * 500 because
15 * 15* 15 * 500 is the same as writing it as 15^3 * 500. This meaning you multiply the number 15 by itself 3 times, not add it 3 times, which is what
45 * 500 was showing. I hope this helped.
Answer:
unreadable score = 35
Step-by-step explanation:
We are trying to find the score of one exam that is no longer readable, let's give that score the name "x". we can also give the addition of the rest of 9 readable s scores the letter "R".
There are two things we know, and for which we are going to create equations containing the unknowns "x", and "R":
1) The mean score of ALL exams (including the unreadable one) is 80
so the equation to represent this statement is:
mean of ALL exams = 80
By writing the mean of ALL scores (as the total of all scores added including "x") we can re-write the equation as:

since the mean is the addition of all values divided the total number of exams.
in a similar way we can write what the mean of just the readable exams is:
(notice that this time we don't include the grade x in the addition, and we divide by 9 instead of 10 because only 9 exams are being considered for this mean.
Based on the equation above, we can find what "R" is by multiplying both sides by 9:

Therefore we can now use this value of R in the very first equation we created, and solve for "x":

Answer: 51 students
Step-by-step explanation: 850 divided by 100= Ans
Ans times 6= 51
*Hope this helps
The equation would be 28= 2r