I myself would rearrange the problem.
But I also think that the parenthesis go like this
(4x+12)
Asuming that the x is multiplying not a variable it would be 5+(4x12)-1 or 4+(4x12)
its pemdas. Do the parenthrses first then work left to right. Wait Is the x a variable or a multiplication sign.
You already doing this in fifth grade. I didn't start those problems until 7th grade and I am in 9th grade now and still learning those problems.
I learned pre calc math in 8th grade. It was only one unit though so idk if it really counts.