16-20= 4 so 4/20 is 0.2 or 20%. To get percentage move decimal to the right two times :)
Answer:
Sir please check the question, its wrong.
Answer: 25
Step-by-step explanation: (x-a)² = x² - 2ax + a²
From x² - 10x + k we deduce that 10x = 2·5x and a = 5
Then k = 5²2
