Answer:
25
Step-by-step explanation:

Use following log property:

Take log of both sides

Distribute left side, isolate 'x'
TOTAL NO.OF ANIMALS IN FARMHOUSE=42
RATIO OF COW : BUFFALO=5:9
LET THE NO.OF COWS BE 5X AND BUFFALOES BE 9X
5X + 9X =42
14X=42
X = 42/14
X= 3
TOTAL NO.OF COWS = 5 x 3 =15
TOTAL NO.OF BUFFALOES = 9 x 3 = 27
If you know the derivative
of some function
, you can tell exactly who
is, up to an additive, constant term. In fact, knowing
, you have

In your case, we have

So, the integral is almost immediate:

So, up to some constant additive term, our function is 
To fix this constant, we know that the function passes through the point (6,10), so we have

And so our function is 
If we want to know when this function equals 6, we simply have to ask
and solve for x, so we have

130 because 2 is less than 5