Assuming the exponent of (2) in the equation is (t/4):
P = 270 * 2^(t/4)
P/270 = 2^(t/4)
log2 (P/270) = log2 (2^(t/4))
log2 (P/270) = t/4
t = 4*log2 (P/270)
Now, assuming t is the exponent of (2), we have:
P = 270 * (2^t)/4
4P/270 = 2^t
log2 (4P/270) = log2 (2^t)
log2 (4P/270) = t
t = log2 (4) + log2 (P/270) = 2 + log2 (P/270)