It is a very high probability. If you role two dice no matter what you will get 12 or less.
1/3(21 - 3a) = 6 - a
7 - a = 6 - a
7 = 6
Therefore, the equation has no solution.
Answer:
DNE
Step-by-step explanation:
Given that two particles travel along the space curves

To find the points of intersection:
At points of intersection both coordinates should be equal.
i.e. r1 =r2
Equate corresponding coordinates

I equation gives t =-1
Substitute in II equation to get 
i.e. t cannot be real
Hence no point of intersection
DNE