Altering Parameters for IF Formula

I need to modify the following formula, =IF(G5=-105,-105,-G5-IF(ABS(G5)>251,40,IF(AND(ABS(G5)>221,ABS(G5)<251),30,IF(AND(ABS(G5)>180,ABS(G5)<221),20,IF(AND(ABS(G5)>=100,ABS(G5)<181),10,105))))) so that I get the following IF-THEN results:

IF G= -105 then value of I = -105

IF G = -110 to -160 then value of I = (100 to 150) -10
IF G = -165 to -200 then value of I = (150 to 185) -15
IF G = -205 to -245 then value of I = (185 to 225) -20
IF G = -250 to -275 then value of I = (225 to 250) -25
IF G = -280 to -315 then value of I = (250 to 285) -30
IF G = -320 to -350 then value of I = (285 to 315) -35
IF G = -355 or lower then value of I = (315 to ....) -40

And also...

IF G = 100 to 150 then value of I = (-110 to -160)
IF G = 150 to 185 then value of I = (-165 to -200)
IF G = 185 to 225 then value of I = (-205 to -245)
IF G = 225 to 250 then value of I = (-250 to 275)
IF G = 250 to 285 then value of I = (-280 to -315)
IF G = 285 to 315 then value of I = (-320 to -350)
IF G = 315 or higher then value of I = (-355 to ....)

Attached is a sample that should help. Thanks.