ok so 48÷4 is each side since square sides are equal that is 12 ×12 which is a area of 144
Step-by-step explanation:
Because the length of ST is calculated using pythagorean theorem:

Where the square of the hypotenuse is equal to the sum of squares of the other two sides of a right triangle. In this case, the hypotenuse is ST and the other two sides are distances between S and T over the X and Y axis. Those are easily calculated:

Where x is the distance between S and T over X axis and Y distance over Y axis, sx and tx are X coordinates of S and T, sy and ty are Y coordinates of S and T.
Using that formula, you get that y = 17 and x = 8.
Back to the pythagorean theorem, if we put those number in the formula of the pythagorean theorem, we get something like this:

And finally, the correct answer is in fact 353.
You can use the measure of 112 on the similar shape to find b, as they are same side exterior angles. From there, you can find both a and c, because a/b and b/c are supplementary angles.
a = 68 degrees
c = 68 degrees