51.8 + (-0.8) i dont like how you suposse to have20 letters

Kylie explained that (-4x+9)^2 will result in a difference of squares because (-4x+9)^2 (-4x+9)^2 =(-4x)^2+(9)^2=16x^2+81

Aadc is formed by reflecting aabc across line segment ac, as shown in the figure. if the length of ac is 4 units, the area of aadc is square units.

Zahra wants the equation below to have an infinite number of solutions when the missing number is placed in the box.