Hi
Stephen and his five friends = 6 people at the restaurant
Let's call X the amount of the bill.
so if X/6 = 13.21
X = 13.21 * 6
X = 79.26
We know: the sum of measures of triangle angles is 180°.
Therefore we have the equation

Substitute
:

<h3>Answer: 180 - 7x</h3>
Five times a minus three in parentheses
I believe the answer is go8ing to be b