Easy way:If Statement

can someone help with this "if statement"?
I am new on this.....I cannot get it to work
is there any other way to do this?

=IF(AND(A12>71012,A12<71025),D12*0.265,IF(AND(A12>76001,A12<76010),D12*0.315,IF(A12=76001,D12*0.185,IF(AND(A12>74009,A12<74018),D12*0.475,IF(AND(A12>75002,A12<75014),D12*0.42,IF(A12=75001,D12*0.42,IF(A12=75002,D12*0.27,IF(AND(A12>72011,A12<72015),D12*0.302,IF(AND(A12>72014,A12<72018),D12*0.252,IF(A12=72011,D12*0.252,IF(A12=72010,D12*0.202," ")))))))))))

Thank you for your help
I tried to use nested page.

but:
=if(onetosix,onetosix,seventotwelve)

I got to this point. Naming my first formula "onetosix" works fine but "seventotwelve" wont work. I noticed that when I go back to my formula it deletes my "if" statements. so it says "=and( " instead of =if(and(...." .
any idea what's going on?

Thank You very much. Problem solved