Answer:
First Q: The smallest value for which n works is 11.
Second Q: Smallest here is 17.
Third Q: I don't know this one, sorry!
Fourth Q: n is -10.
Step-by-step explanation:
For the first two questions, find the smallest common factor between the two numbers (subtract the remainder).
Q1:
First, subtract the remainders from the numbers (2149 - 4 = 2145; 1578 - 5 = 1573)
Then, list the factors
2145: 1, 3, 5, 11, 13, 15, 33, 39, 55, 65, 143, 165, 195, 429, 715, 2145
1573: 1, 11, 13, 121, 143, 1573
These two numbers share 11 and 13 in common. 11 is the smaller of these, so it is the smallest value n can work.
Q2:
Repeat the steps from Q1.
12650 - 2 = 12648; 5800 - 3 = 5797
12648: 1, 2, 3, 4, 6, 8, 12, 17, 24, 31, 34, 51, 62, 68, 93, 102, 124, 136, 186, 204, 248, 372, 408, 527, 744, 1054, 1581, 2108, 3162, 4216, 6324, 12648
5797: 1, 11, 13, 17, 31, 187, 341, 527, 5797
These two share 17, 31, and 527 in common. 17 is the smallest of these, so it is the smallest value n can work.
Q4 (I don't know how to do Q3 yet):
2n + 25 = n + 15
Subtract n from both sides
n + 25 = 15
n = 15 - 25
Subtract 25 from 15 to get -10
n = -10
Again, I don't know how to do Question 3 yet. Sorry for the inconvenience! Anyhow I hope the rest of this was helpful!