Which relation is a function of x?

What is the missing statement in step 4? ? rts ? ? vtu and ? rtu ? ? vts ? rts ? ? rvs and ? rtu ? ? stv ? vrs ? ? vru and ? usr ? ? usv ? vur ? ? vus and ? uvs ? ? sru

How to simply and write the answer n a whole number

Combine like terms to create an equivalent expression. make sure to simplify coefficients and constants as well. -6/5-2/3v+4/15+1/3v