Question 1125450
<pre>
                           SPEED      TIME           DISTANCE

Singapore to Penang         x-30      700/(x-30)     700

Penang to Singapore (car)    x        700/x          700

TOTAL                                  20
</pre>
{{{700/(x-30)+700/x=20}}}

-

{{{35/(x-30)+35/x=1}}}

{{{35x+35(x-30)=x^2-30x}}}

{{{70x-1050=x^2-30x}}}

{{{x^2-30x-70x+1050=0}}}

{{{x^2-100x+1050}}}----------the equation you wanted