Plz read these and amwser, I’m confused

If 10 men take 18 days to mow 60 acres of grass, how long will 15 men take to mow 80 acres?

Ntriangle abc, m∠a = 35° and m∠b = 40°, and a=9. which equation should you solve to find b?

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! )