Answer:
a = 19
Step-by-step explanation:
If the rate of change is -8, subtract 8 from your y value of 27. And if 19 is correct, you should be able to subtract 8, and get 11 as the next number in the function, which you do, so 19 is the value of a.
m=25/12
multiply the reciprocal of 2/5 on both sides
y² = x² - z²
x² - y² = z²
Transpose y the other side
x² - z² = y²
or
153.8 I guess... this is your answer