=IF(A1<20,0,IF(A1<30,A1*2,IF(A1<40,A1*4,IF(A1<50,A1*6+100,A1*8+100))))
=IF(A1<20,0,IF(A1>=50,A1*8+100,IF(A1>=40,6*A1+100,IF(A1>=30,4*A1,A1*2))))
=IF(A1<40,,100)+LOOKUP(A1,{0,0;20,2;30,4;40,6;50,8})*A1
=IF(A1>=50,A1*8+100,IF(A1>=40,A1*6+100,IF(A1>=30,A1*4,IF(A1>=20,A1*2,0))))