Idon't have a great understanding of simplifying polynomials

simplify the following polynomials, showing all of your work for full credit.

part a: simplify (x − 8) + (x + 3) (2 points)

part b: simplify (4x − 7) − (13x + 2) (3 points)

What is the pattern in the values as the exponents increase?

Write an equation in slope intercept form of the line passes through the given point and is parallel to the graph of the given equation (0,0); y=3/8 x+2

The management of a supermarket wants to adopt a new promotional policy of giving a free gift to every customer who spends more than a certain amount per visit at this supermarket. the expectation of the management is that after this promotional policy is advertised, the expenditures for all customers at this supermarket will be normally distributed with a mean of $95 and a standard deviation of $20. if the management wants to give free gifts to at most 10% of the customers, what should the amount be above which a customer would receive a free gift?