Answer:

Step-by-step explanation:
By definition if two events are mutually exclusive then they are disjoint events, that is, they can not occur at the same time.
In general terms we say that events are mutually exclusive, then:

In this case we have that

But A and B are mutually exclusive events, then 
12 is the answer
hope this helps!
I am taking 7I+x to mean 71+ x.
Answer: y=1.837
Step-by-step explanation:
Step 1
Let y is inversely proportional to 7I+x be mathematically be written as
y ∝ 1/7I+x
Introducing our proportionality of constant , K we have that
y ∝ 1/7I+x
y =K 1/7I+x
y= K/ 7I+xh
Step 2
so when x= 8, and y =2, k becomes
y= K/ 7I+x
k= y x (7I+x)
=2 x (71 + 8)
2x 79
=158
when x= 15, y =?
y= K/ 7I+x
y= 158/ 71 + 15
y=158/86
y=1.837