Step-by-step explanation:
Given bi-quadratic equation is:
Substituting
given bi-quadratic equation reduces in the form of following quadratic equation:
Let us factorize the above quadratic equation:
Since square root of a negative number cannot be found, so:

Answer:
1/2
Step-by-step explanation:
x + 9 = -15x = [1]
x - x + 9 = -15x -x = 1
9 - 1 = -16x
8 = 16x
8/16 = 16/16x
1/2 = x
Hope this helps
Its 11/12 , you need to divide the "wanted results" (every dog which is either black, with spots or both ) by every every possible result ( all dogs ). so 11/12=0.92