Can you solve for t? (At-B)/(C-B(1-3t)=4

I'm assuming there is another close parenthesis on the right side of the 3t


(At-B)/(C-B(1-3t)) = 4
multiply both sides by (C-B(1-3t))

At-B = 4(C-B(1-3t))
simplify the right side
At-B = 4(C - 1B + 3Bt)
At - B = 4C - 4B + 12Bt
move the 12Bt to the left side by subtraction
At - B - 12Bt = 4C - 4B
now move the B to right side by adding it to both sides
At - B + B - 12Bt = 4C - 4B + B
At - 12Bt = 4C - 3B
factor out the t on the left side

t(A - 12B) = 4C - 3B
divide both sides by A - 12B


4C - 3B
----------- = t
A - 12B

Do you mean (At -B)/(C - B(1-3t)) = 4?

If so, then At - B = 4C - 4B + 12t and then At - 12t = 4C - 3B and then t(A-12) = 4C - 3B
so t = (4C - 3B)/(A - 12)