Answer:
1/3
Step-by-step explanation:
x(x-2)+2x+36-3x+46=100; x>0
x²-2x+2x-3x+82-100=0
x²-3x-18=0
x²-6x+3x-18=0
x(x-6)+3(x-6)=0
(x+3)(x-6)=0 => x=6
=> 6(6-2)+2*6=36 stamps in the 20th century
2x=2*6=12 stamps in the 20th century and British stamps
Probability=12/36=1/3
