Question 630643
<pre>
The other tutor did not simplify the answer, but left
fractions within a fraction.

{{{1/B}}} = {{{1/s}}} +{{{1/t}}}

Since none of the denominators have any common factors, the LCD
is just their product B·s·t.  Write that as {{{B*s*t/1}}} and multiply
every term by that

{{{1/B}}}·{{{B*s*t/1}}} = {{{1/s}}}·{{{B*s*t/1}}} +{{{1/t}}}·{{{B*s*t/1}}}

Cancel:

{{{1/cross(B)}}}·{{{cross(B)*s*t/1}}} = {{{1/cross(s)}}}·{{{B*cross(s)*t/1}}} +{{{1/cross(t)}}}·{{{B*s*cross(t)/1}}}

s·t = B·t + B·s

Get the terms that has t alone on one side.  So we subtract B·t
from both sides

s·t - B·t = B·s

Next we factor out t on the left side

t·(s - B) = B·s

Now we divide both sides by (s - B)

{{{t*(s - B)/(s - B)}}} = {{{B*s/(s-b)}}}

Cancel the (s - B)'s on the left side:

t = {{{B*s/(s-B)}}}

Edwin</pre>