What is the slope of the line that passes through the points (13, −8) and (−11, 4)?

Nine more than four times a number is the same as one less than twice the number. find the number?

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)

I’m still confused on how to work the percentages