Is it permissible to pay a single expiation for multiple oaths if the value of one expiation is 500 Syrian Pounds and the total due for all expiations is 1500 Syrian Pounds?

If a person takes multiple oaths concerning different matters, then the expiation multiplies according to the number of things sworn upon and the breach of each one. So, if he breaks all the oaths before performing expiation, then he owes an expiation for each oath.

As for a vow that you were unable to fulfill, and the inability was permanent, then you owe another expiation of an oath for it, based on the saying of the Prophet, peace and blessings be upon him: "Whoever takes a vow he cannot fulfill, its expiation is the expiation of an oath."

The expiation of an oath is to feed ten poor persons from the average of what you feed your families, or to clothe them, or to free a slave. If one cannot find [any of these], then it is to fast for three days. The basic principle for expiation is that it should be in the form of food, and it is not permissible to pay its monetary value according to the majority of scholars.