Solve for t:
4 6
-- = --
t+3 1-2t
4/(t+3) = 6/(1-2t)
Multiply both sides by (t+3) and (1-2t).
4(1-2t) = 6(t+3)
Get rid of parentheses.
4 - 8t = 6t +18
You should be able to solve it from here.
I hope this helps. Thanks for asking.