Is 4 x 10^-9 a rational number

What does x = in this equation x+3+2x=x+5

Which expression is equal to (f+g)(x)?

During the election for class president, 40% of the students voted for kellen, and 60% of the students voted for robbie. 500 students voted in total. how many more students voted for robbie than for kellen? answer with work : )