NEED HELP WITH QUESTIONS 25 & 27 PLEASE!!!

Find the solution of this system of equation -7x+y=-20 9x-3y=36

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! )

Acompound inequality is graphed, and its graph consists of all real numbers. which open scentence could have resulted in this solution set r> 3 or r< -2. r< 3 or r< -2. r> 3 or r> -2. r< 3 or r> -2 plz asap