Find a number whose sum is 36 and their difference is 10 what are the numbers and its calculation

If you could answer these your a life saver

Find the perimeter of the triangle with vertices  d(3, 4),  e(8, 7), and  f(5, 9). do not round before calculating the perimeter. after calculating the perimeter, round your answer to the nearest tenth.  

Subtract and simplify. (-y^2 – 4y - 8) – (-4y^2 – 6y + 3) show how you got the answer if your answer is right i will mark you