" 8 more "....means add 8
" twice a number " means multiply the number by 2
ur expression is : 2n + 8
It looks like you might have intended to say the roots are 7 + i and 5 - i, judging by the extra space between 7 and i.
The simplest polynomial with these characteristics would be

but seeing as each of the options appears to be a quartic polynomial, I suspect f(x) is also supposed to have only real coefficients. In that case, we need to pair up any complex root with its conjugate to "complete" f(x). We end up with

which appears to most closely resemble the third option. Upon expanding, we see f(x) does indeed have real coefficients:

A came to C, C was supposed to go to A
To find the number of days, divide the total swam by the average:
Days = 48 / 3.2 = 15
They swam for 15 days.
X>-6 is what i believe the answer is.
hope this helps!