Dev gets 10% of votes joe gets twice as many votes holly what percentage of the votes does the winer get?

Inferring that they are the only three players, all of their votes equal to 100%. If Dev gets 10%, that leaves 90% for Joe & Holly. You are now looking for a number that , when doubled adds to 90%.
Using an equation: a+2a=90
Solve for a.
3a=90 a=90/3

Now we have 10%,30%, & 60%

Idon’t actually know but have you asked google yet

Yes, two vertical lines can be complementary