Match the numbers with the correct label

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! )

Which equation can be solved to find x the measure of jk in the apex

Can someone show me step by step how to do this?