Ab+ac=a(b+c)
a is common factor
factor
6ab=2*3*a*b
9bc=3*3*b*c
common factor is 3*b or 3b
3b(2a)+3b(3c)=3b(2a+3c)
The fourth side = f, now let's solve for f
value of fourth side = f = 96 km
Seven times one equals seven itself. 'Cause any number times 1 is it's number itself
if events X and Y are independent, then for intersection we multiply the probability
P(Y∩X) = P(Y) * P(X)
We know that

Now we replace P(Y) * P(X) for P(Y∩X)

Cancel out P(X)
So 
Like that

Now we replace P(X) * P(Y) for P(X∩Y)

Cancel out P(Y)
So 
P(Y | X) = P(Y) and P(X | Y) = P(X) are true