conversations.from: human
conversations.value: This math problem has got me stumped: A fast-food chain offers free delivery for a minimum purchase of $18. Danny ordered 2 quarter-pounder burgers for $3.20 each, 2 large fries that cost $1.90 each, and 2 milkshakes that cost $2.40 each. How much more worth of food should he order to avail of the free delivery?
  Can you show me the way?
conversations.from: assistant
conversations.value: Two quarter-pounder burgers cost $3.20 x 2 = $6.40.
  Two large fries cost $1.90 x 2 = $3.80.
  Two milkshakes cost $2.40 x 2 = $4.80.
  The total amount spent for the burgers, fries, and shakes is $6.40 + $3.80 + $4.80 = $15.
  Therefore, he should order $18 - $15 = $3 worth of additional food to take advantage of the free food delivery.