I am trying to produce a formula that does the following:

If the value of (a+b+c+d) = 1 then cell e must show 500
if the value of (a+b+c+d) = 2 then cell e must show 1000
if the value of (a+b+c+d) <= 3 then cell e must show 1000+(((a+b+c+d)-2)*300)
How do I nest the ifs correctly to get this.

Thank you
JBS