8(3a+6)=2a-4 how do you do this problem i keep getting a number with an insane amount of decimals

Need solving this second acceleration problem.

Aculture started with 3000 bacteria. after 5 hours it grew to 3900 bacteria. predict how many bacteria will be present after 9 hours

Write 5 in the form of a/b using integers to show it as a rational number