How do I get my High School GPA from a 3.5 to a 3.7 over the next 3 semesters?

Okay, so I am a Junior in high school, and I currently have a cumulative GPA of a 3.5 from the 14 credits that I have completed Freshmen and Sophomore year.
By the time I need to submit my cumulative GPA to colleges this fall, I would’ve completed 3 semesters which correlate to 21 credits.
So with that being said, what GPA will I need to obtain and maintain over the next three semesters in order to raise my cumulative GPA from a 3.5 to a 3.7 for when I submit my GPA to colleges in the fall?
Also is obtaining a final cumulative of a 3.8 a reach?
I take all double honors classes with a couple of AP and IB classes mixed in.
Thank You (:

If I’m understanding it correctly, you get 7 credits per year and are asking what you would need to get this year in order to boost your GPA from a 3.5 to 3.7? The several uses of “semester” are a bit confusing to me. Correct me if I’m wrong…
[(3.5 GPA)(14 credits) + (X GPA)(7 credits from this year)]/21 = 3.7
49+7x=77.7
7x=28.7
x=4.1

You would need a 4.1 GPA for THIS year to bring up your OVERALL cumulative GPA from a 3.5 to a 3.7 unweighted.