For what value(s) of k will the relation not be a function?

B = {(0.5k–5, 10), (k+7, 4)}

What is the absolute value of the complex number -4-sqrt2i

Money off coupons have been circulated to 300 households. only 2/5 of these were redeemed (used) in the local supermarket to get a free shampoo. what fraction of coupons were unused? (ps: write how you got the answer)

An octagonal prism has jow many lateral faces?