Along with your conference flyer, your proof of attendance and map showing mileage, your original gas receipt must be included.  Many don't understand there is a difference in reimbursable receipts.  Please see the examples showing what is accepted for reimbursement and what isn't:
Gas Receipts
You Belong at UCR

All programs, services, and events offered through Student Affairs are open to everyone, consistent with federal and state law and the University of California’s nondiscrimination policies. Whether you’re seeking support, joining a community, or participating in campus life, every effort is made to ensure your experience is inclusive, respectful, and accessible, regardless of background or identity.

To learn more, visit the UC Nondiscrimination Statement or the Nondiscrimination Policy Statement for University of California Publications Regarding Student-Related Matters.