-x + y + z (A) If x-y +: x + y-2 = 21 then find the value of 21 -.

If x-y=4 and x y=21 , find the value of x^3-y^3dot

If x-y=4 and xy=21, find the value of x^(3)-y^(3)

If 7/12xy=21 , then find the minimum value of 5(x+y) .

If x+y +z= 21 then find the maximum value of (x-2) (y-1) (z+ 9)

If 3x + 5y = 21 and 2x +3y = 13 , then find the values of x and y .

If (i) 4x+5y=83 and (3x)/(2y)=(21)/(22), then what is the value of y-x? (ii) (x)/(4)-(x-3)/(6)=1 then find the value of x.

If (2x)/3=(4y)/5=(7z)/9 then find the value of (4x+12y-21z)/(3y) .