Needing help with IF, AND Function?

I am trying to use multiple formulas to come to a final outcome. The final formula is fighting back.

In words:
if g7 is >0 and <=30... i7 will be the number 1000
if g7 is >30 and <=60... i7 will be the number 1900
if g7 is >60 and <=90... i7 will be the number 2900
if g7 is >90 and <=120... i7 will be the number 3900
if g7 is >120 and <=150... i7 will be the number 4900
if g7 is >150 and <=180... i7 will be the number 5900
if g7 is >180 and <=210... i7 will be the number 6900
if g7 is >210 and <=240... i7 will be the number 7900
if g7 is >240 and <=270... i7 will be the number 8900
if g7 is >270 and <=300... i7 will be the number 9900

When I try and put all this into one formula, I seem to have an error somewhere. Do I need to use another type of functions? Please help.