Don't panic, this is a linear combiantion of vector.

Write the vectors in column and you will see that you have :

All the first entries of the vectors to the left must equal one,

All the second entries of the vectors to left must equal 0,

All the third entries of the vectors to the left must equal 1,

You are left with a system of linear equations as follow:

I hope that you can finish this, you have two equations and two unknowns because you know that p =1 from the first equation.

Cheers