If `a,b,c and d` satisfy the equation `a+7b + 3c + 5d=0, 8a + 4b + 6c + 2d=-16,`` 2a+6b + 4c+8d =16,5a+3b+7c+d=-16` then `(a+d)(b+c)` equation

If a, b, c, d satisfy the equation a + 7b + 3c + 5d = 0 , 8a + 4b + 6c + 2d = - 16 , 2a + 6b + 4c + 8d =16 and 5a + 3b + 7c + d = -16 then the value of (a + d) (b + c) =______

If 2a =3b =7c =5d =210 then a +b+c+d is

If a : b = 2:3, b: c= 4:5 and c:d=6:7, then a:d=

If a: b= 2: 3, b: c= 4: 5 and c: d= 6: 7 , find : a: b: c:d .

"a b c - a - c - - b - d ? ? ? ?" "- 4 - 5 8 - - - - - 3 5 - - - -"

If a+1=b+2=c+3=d+4=a+b+c+d+5, then (a+b+c+d) is equal to