Ok so we have {{{1/2t=-7}}} What you can do in algebra is flip both sides of an equation. So {{{1/2t}}} will become {{{2t/1}}} and {{{-7}}} which is really {{{-7/1}}} will become {{{-1/7}}}
So now we have.
{{{2t=-1/7}}} Now you divide both sides by two. Dividing a fraction can be confusing so you can multiply by {{{1/2}}} instead of dividing by 2.
{{{t=(-1/7)*(1/2)}}}
Giving us.
{{{t=-1/14}}}