Process:
1. 21+24n= 7
2. 24n= 7 - 21
3. 24n= -14
Answ: n= -7/12
Sum/difference:
Let
This means that
Now, assume that 
is rational. The sum/difference of two rational numbers is still rational (so 5-x is rational), and the division by 3 doesn't change this. So, you have that the square root of 8 equals a rational number, which is false. The mistake must have been supposing that was rational, which proves that the sum/difference of the two given terms was irrational
Multiplication/division:
The logic is actually the same: if we multiply the two terms we get
if again we assume x to be rational, we have
But if x is rational, so is -x/15, and again we come to a contradiction: we have the square root of 8 on one side, which is irrational, and -x/15 on the other, which is rational. So, again, x must have been irrational. You can prove the same claim for the division in a totally similar fashion.
Answer:
0.7 hours
Step-by-step explanation:
Given that Irina was able to make the same distance from work to home in 0.4 of an hour at 27 miles per hour, we can use this rate and time to find the distance she travels to and from work using the general formula:
d = rt, where d=distance, r = rate and t = time
d = 27(0.4) = 10.8 miles
Since the distance from Irina's home to work is 10.8 miles, we can again use the formula 'd = rt' to find the time it takes her to bike to work at a rate of 16 miles per hour and solving for time, 't':
10.8 = (16)t
t = 0.7 hours
