What is the average rate of change over the interval 1

You can find the constant of proportionality by finding the ratio of

Pyotr tchaikovsky sporting goods operates on a 45% overhead based on the selling price, which results in an overhead of $65.34 on the newest version of an air hockey game set. if the air hockey game set costs pyotr tchaikovsky sports $49.32, find the selling price, the markup, and the net profit.

X+ y = 5 ; x - y =3 solve using linear combination