James buys pistachios for $10 per can.  Each can is 5 ounces.  He eats 30 ounces of pistachios every 5 days.  How much does he spend on pistachios per week?
How much do the pistachios cost per ounce? ** The pistachios cost 10/5=$<<10/5=2>>2 per ounce
How many ounces of pistachios does James eat in a day? ** He eats 30/5=<<30/5=6>>6 ounces of pistachios a day
How much does James spend on pistachios in a day? ** So he spends 6*2=$<<6*2=12>>12 per day on pistachios
How much does James spend on pistachios per week? ** So he spends 12*7=$<<12*7=84>>84 per week
#### 84