What system of measurement does the u. s. use

The United States Code refers to these units as "traditional systems ofweights and measures". Other common ways of referring to the system in the U.S. are: "Standard", "Customary", or, erroneously: "Imperial", or "English" (which refers to the pre-1824 reform measures used throughout the British Empire).

m=9

step-by-step explanation:

7m+8=71 subtract   8 from 71 which is 63 than divide it by 7m   equal 9.