(x-4)(x-5)+(3-x)(x-2)=0

x^2 - 5x -4x + 20 + 3x - 6 - x^2 + 2x = 0
-9x + 14 + 5x = 0
-4x = - 14 
x = 14/4 
x = 3,5

x²-5x-4x+20+3x-6-x²+2x=0
-9x+5x=-20+6
-4x=-14
x=14/4
x=3,5