I cannot see the drop down answers, but they should look like the following:
1) the value of m would remain the same because b does not affect m's value. The price per pound is not effected by what is spent on other ingredients.
2) the value of b would remain the same because the price per pound does not effect the amount spent on other ingredients.
3) if m is tripled, then mx is also tripled; it increases.
Example: if you bought 3 lbs of potatoes at $1.00 a pound, they would cost $3.00. If the price per pound tripled to $3.00 and you bought 3 lbs, you would spend $9.00. $9.00 is tripled the original cost of $3.00.
ANSWER: 1) m would remain the same; 2) b would remain the same; 3) m is tripled/increased depending on answer options in drop down menu.
Hope this helps! :)