\[\sum_{n=1}^{7} 2(-2)^{n-1}\]
I think it is B but I might be wrong
<span>Given that there are 50 campers at day camp and 10
counselors.
The ratio of campers to counselors as a fraction is given by

.
Using equivalent fractions we have

.
Thus, the related rate and unit
rate to the ratio of campers to counselors is given by

.
The unit rate indicates that for every counselor, there are 5 campers.</span>
Uhh, these give me a headache, I think number 2 is array..