Here's a table that shows the result of this conversion. In the first column we see the number of burgers consumed, in the second the total utility from burgers as before, in the third, the opportunity cost, and in the fourth, the quotient -- the benefit from consuming burgers, measured in money.

In ordinary terms (for example) this table tells us that three burgers give Joe Blow as much utility as other goods and services (such as cokes) that he could buy with 17 dollars. So 17 dollars is the money measure of his subjective benefit from burgers.

Of course, if the opportunity cost of 10 were to change, then the whole schedule of benefits from different quantities of burgers would shift -- and that might happen, if, for example, the price of cokes were to change. But that should come as no surprise. We know that a change in the price of some goods and services would change the purchasing power of income, and it makes sense (to me, anyway) that the "marginal utility of income" would change when the purchasing power of the income changes.