What value must k take in order for the following expression to be greater than zero? 3/k - 5/7

Solve the system of equations. y= 2x y= x^2 - 15

Can someone me out here and the tell me the greatest common factor

Frank owns a $141,000 home, for which he has a 30-year mortgage in the amount of $700 a month. once he has paid off mortgage, how much will he have paid in investment? a. $111,000 b. $109,000 c. $120,000 d. $141,000