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