STEP 1:
multiply number of pounds purchased by price per pound
= 3.4 pounds * $4.25 per pound
= $14.45 total cost
STEP 2:
subtract total cost of purchase (step 1) from amount she gave cashier ($20.00)
= $20.00 - $14.45
= $5.55 amount received back from cashier
ANSWER: (B) $5.55 received back
Hope this helps! :)