Step by step pls not only one thing

Use the elimination method to solve the systems of equations.choose the correct ordered pair. 7x+4y=39

Michelle is planting flowers in her garden. she wants the ratio of daises to carnations to be 3 to 2. michelle wants to plant a total of 35 flowers. how many daises should she plant?

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! )