You can
put this solution on YOUR website!if you need to solve for x, then you need every term with x in it on one side:
nx=2nx-21n
nx-2nx=-21n
x(n-2n)=-21n
x(-n)=-21n
x = (-21n)/(-n)
x = 21
since the - and the - cancel and the n and the n cancel
jon.