Friendly phone= 0.06×400=24; 0.25×400= 100; 100+24+3.95=127.95; 127.95×4= $511.8
Chatter= 0.098 × 400= 39.2; 0.192 × 400= 76.8; 76.8+39.2+4.95= 120.95; 120.95 × 4= $483.8
Phone A Lot= 0.089 × 400= 35.6; 0.24 × 400= 96; 35.6 + 96= 131.6;
131.6 × 4= $526.4
Chatter < Friendly phone < Phone A Lot
$483.8 < $511.8 < $526.4
The cheapest one would be Chatter= $483.8
Hope this helps :)
