We can substitute I with 120 since that's how much he made in one day.
120 = 7n + 50
~Subtract 50 to both sides
120 - 50 = 7n + 50 - 50
~Simplify
70 = 7n
~Divide 7 to both sides
70/7 = 7n/7
~Simplify
10 = n
Therefore, the saleman made 10 sales.
Best of Luck!
