The coefficients of x2y2, yzt2 and xyzt in the expansion of (r + y + z + t)4 are in the ratio

Coefficient of x2y2 in (x+y+z+t)4=4!2!2!=6 and coefficient of yzt2 in⁡(x+y+z+t)4=4!1!1!1!2!=12AIso, coefficient of xyzt in (x+y+z+t)4=4!111!11!=24 .'. Required ratio is 6 :12:24 = 1:2:4