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.