Add 6x+2y=-2 and 3x-2y=-5

Find and simplify an expression for the area of five rows of x squares with side lengths of x centimeters.

3x = 729 solve for x plz . it's urgent. will mark

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! )