Question 193268
usually  to  solve  linear equation  with  2  unknowns,  we  have  two  equations  explaining  the  relationship.

since  we  only  have  one,  we  can  describe  the  line,  which  will  define  all  the  relationships.

-2x+5y =15

setting  up  a  T  box

"X",,,,,,,,,,"Y",,,,,,,,,,,,calc

0,,,,,,,,,,,,,3,,,,,,,,,5y=15+2(0),  y=3
5,,,,,,,,,,,,,5,,,,,,,,,5y=15+2(5)=25,,  y=5
10,,,,,,,,,,,7,,,,,,,,,5y=15+2(10)=35, y=7
15,,,,,,,,,,,9,,,,,,,,,5y=15+2(15)=45, y=9
20,,,,,,,,,,11,,,,,,,,5y=15+2(20)=55, y=11

hopefully  this  gets  you  started