I need help with this question

2x + 1/2 = -5

In the diagram of circle o, what is the measure of zabc?

In which direction does the left side of the graph of this function point? a(x) = 3x - x2 + 4x - 2

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )