Simplify 3 square root 10+7square root 15-6square root 10-4square root 15?

Josephine has a great garden with and area of 2x2 + x - 6 square feet

If square root x = -7, then x= -49 true or false

Isabel graphed the following system of equations. 2x – y = 6 y = -3x + 4 she came up with the solution (2,-2). what were the 3 steps she did to get that solution? (make sure they are in the correct order)