ANSWER

EXPLANATION
Method 1
Vertically opposite angles are equal, therefore

This implies that,

We simplify to get,

Dividing through by 3 gives,

Also,

This implies that,

We simplify the right hand side to get,

We divide both sides both sides by 2 to get,



Method 2
Angles on straight line sums to 180°.

This implies that,




Also,






10/6= 1.666666667
12/7.2 = 1.6666666667
3 x 1.66666666667 = 5
m = 5
From the definition of conditional probability:

By the law of total probability,



Since

we end up with

The possible points are 3 5 7 9 11 13 15
so the answer is 7