I'm terrible at math, so I'm sorry if I'm totally wrong, but I'm assuming you just take the average:
20+28=48m
48/2=24m
On average, it may take them 24m if they work together.
The signs of the numbers in the problem matter because if a number is negative in the equation than you're answer could be negative. ex. -3/9= -3 but if the negative sign wasn't there than the answer would be wrong bc the answer would be positive.
hope thats what you need hope it helps.
Answer:
2. 27
3. Option C. 3, 5, 9, 17, 33, ...
Step-by-step explanation:
2. The sequence is defined by the explicit function 
Therefore, the 5th term i.e.
of the sequence.
(Answer)
3. The explicit definition is 
Hence, 



Therefore, the option C is the right sequence. (Answer)