Write each algebraic expression described.
The longest interstate highway in the U.S. is I-90, which connects Seattle, Washington, and Boston, Massachusetts. The second longest interstate highway, I- 80 (connecting San Francisco, California, and Teaneck, New Jersey), is 178.5 miles shorter than I-90. If the length of I- 80 is $m$ miles, express the length of I-90 as an algebraic expression in $m$. (Source: U.S. Department of TransportationFederal Highway Administration)