Consider the question. Gary has 30 grams of gold that cost $15 per gram. Anna has 50 grams of gold for the cost of $20 per gram. How much is the cost of their gold combined?
 If the answer is '1450'; explain the reasoning:
The cost of Gary’s gold is 30 * $15 = $450. The cost of Anna’s gold is 50 * $20 = $1000. The total cost of their gold is $450 + $1000 = $1450.