Given
y is directly proportional to square root of x.
And, y=-67, when x=9.
To find: y, if x=81.
Step-by-step explanation:
It is given that,
y is proportional to square root of x.
That implies,

Then, for x=9 and y=-67,

That is,

Then, for x=81,

Hence, the value of y is -201.