3△6
= (A*3+6)/(2*3*6) = (A+2)/12
4△5
= (A*4+5)/(2*4*5) = (4A+5)/40
则有方程
(A+2)/12 = (4A+5)/40
解得A = 2.5
4△6
= (2.5*4 + 6)/ (2*4*6)
= 16/48
= 1/3
3△6
= (A*3+6)/(2*3*6) = (A+2)/12
4△5
= (A*4+5)/(2*4*5) = (4A+5)/40
则有方程
(A+2)/12 = (4A+5)/40
解得A = 2.5
4△6
= (2.5*4 + 6)/ (2*4*6)
= 16/48
= 1/3