Answer :

mariamikayla
[tex]79*20=(80*20)-(n*18) \\\\ 1580=1600-18n \\\\ 1580-1600=18n \\\\ -20=18n \ |:2 \\\\ -10=9n \\\\ \boxed{n=-\frac{10}{9}}[/tex]
xXxGirxXx
79 × 20 = (80 × 20) - (n × 18)        :First, multiply what is on the left of the equation

1580 = (80 × 20) - (n × 18)            :Then, solve for what is in the first parenthesis

1580 = (1600) - (n × 18)                :Then, act like there is a 1 in front of the negative                                                                        and distribute

1580 = 1600 - 18n                         :Then, subtract 1600 from both sides

-20 = -18n                                      :Then, divide the whole equation by -18 

1.1 = n

Your final answer is:

n = 1.1