The problem says that there are formulas for the diagonals of a rectangle. they are both givan in terms of x
Now, recall that the diagonals of a rectangle should be equal to each other, therefore those two expressions must equal ech other
2 x + 3 = 4 x - 11
Now let's solve for x:
move all terms with "x" to one side of the equation, and all "numerical" terms to the other side:
start by subtracting 2x from both sides:
3 = 4 x - 2 x - 11
3 = 2 x - 11
Now add 11 to both sides:
11 + 3 = 2 x
14 = 2 x
then x is 7
