Can anyone answer question 15 and 16

15) (6x²y³)(3xy²z⁵) = 18x³y⁵z⁵

16) area of square with side lengths (x-3) units

area of a square = a² 
A = (x-3)²
A = (x-3)(x-3)
A = x(x-3) -3(x-3)
A = x² - 3x -3x + 9
A = x² - 6x + 9

Area of a rectangle with a length of x units and a width of (x-5)units

Area of a rectangle = length * width
A = x * (x-5)
A = x(x-5)
A = x² - 5x

Value of x for Area of square and Area of rectangle to be equal.

Area of square = Area of rectangle
x² - 6x + 9 = x² - 5x
x² - x² - 6x + 5x = -9
-x = -9
x = -9/-1
x = 9

x² - 6x + 9 = x² - 5x
9² - 6(9) + 9 = 9² - 5(9)
81 - 54 + 9 = 81 - 45
90 - 54 = 36
36 = 36