Answer :

1/2+-2/5t(+2/5)=1/5t+t(+2/5)
simplify
1/2=2 and 3/5t
change to a decimal
.5 = 2.6t
divide both sides by 2.6
.5/2.6 2.6t/2.6
you get T= .3125
I think taylor answer is correct