Simultaneous Equation question, no clue how to solve it, please help!

Can someone check my answer? you : )

You have a square piece of cardboard that measures 14 inches on each side. to build a box, you cut congruent squares out of each corner of the cardboard. use the picture to find the area of the cardboard you were used to build the box

For the feasibility region shown below find the maximum value of the function p=3x+2y