I would write the missing variable as x. It's what everyone uses.
Anyway, 91 divided by x is 65.
The way we can do this is reverse 65 and x.
91 divided by 65 = x.
91 divided by 1.4 = 65
65 x 1.4 = 91
x (or ?) = 1.4
a. 3 × 10^0
b. 33. 6 × 10^0
c. 57. 6 × 10^2
d. 4. 0 × 10^-7
e. 7. 0 × 10^-1
<h3>What is scientific notation?</h3>
Scientific notation is simply a way of expressing numbers that are too large or small to be written in decimal form.
It may be referred to as standard index form or scientific form.
From the information given, we have;
a. 0. 000003 is written in standard form as;
= 3 × 10^-6 × 3 × 10^6
= 3 × 10^-6 + 3
= 3 × 10^0
= 3
b. 56, 000, 000. 00 is written in standard form as;
= 5. 6 × 10^7 × 6 × 10^-7
= 33. 6 × 10^7 -7
= 33. 6 × 10^0
= 33. 6
c. 8. 0 × 10^-3 × 7. 2 × 10^5
= 57. 6 × 10^-3 + 5
= 57. 6 × 10^2
d. 4. 0 × 10^-3 × 4. 0 × 10^-4
= 4. 0 ^ -3 +(-4)
= 4. 0 × 10^-7
e. 7. 0 × 10^3 × 7. 0 × 10^4
= 7. 0 × 10^ 3-4
= 7. 0 × 10^-1
Thus, scientific notation is also referred to as standard form.
Learn more about scientific notation here:
brainly.com/question/27862246
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Answer
Find out how many seconds faster has Alexandria's time then Adele's time .
To proof
Let us assume that seconds faster has Alexandria's time then Adele's time be x.
As given in the question
Adele Swam the length of the pool in 32.56 seconds. Alexandria swam the length of the pool in 29.4 seconds.
Than the equation becomes
x = 32.56 - 29.4
x = 3.16 seconds
Therefore the 3.16 seconds faster has Alexandria's time then Adele's time .
Hence proved
Answer:
680
Step-by-step explanation:
Use the binomial coefficient where you choose 
numbers out of 
possible numbers and find the total amount of combinations since order does not matter:
Thus, you can make 680 three-non-repeating-number codes
