Question 417690
let bill be x
PLAN A
190+0.3(x-190)
PLAN B
220+0.2(x-220)

PLAN B < PLAN A

220+0.2(x-220)<190+0.3(x-190)
220+0.2x-44<190+0.3x-57
220-190-44+57<0.3x-0.2x
43<0.1x
/0.1
430<x

x>430 will save money under Plan B