Please someone help me

Which expression gives the area of the triangle shown below

What is the simplified form of (3.25x10^3)(7.8x10^6) written in scientific notation?

The linear combination method is applied to a system of equations as shown. 4(.25x + .5y = 3.75) → x + 2y = 15 (4x – 8y = 12) → x – 2y = 3 2x = 18 what is the solution of the system of equations? (1,2) (3,9) (5,5) (9,3)