A/b=c/d solve for c i needto get this done andi dont feel like solving

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! )

How do you find the distance of each number from the mean

Find the measure of angle b in the following triangle