Answer B & C are correct because P(A) + P(B) + P(C) add up to 1
A) multiply equation A by -2 so you get -2x - 2z = -12 and then you can add both equations to eliminate z
I got 7.1 x 10^(-11) but it's been a few years so I could've done it wrong
Answer:
for the number 13
Step-by-step explanation:

by Pythagoras theorem
x= √81+36
x= √117
punch square root of 117 with a calculator, I don't have one now