Question 998268
<pre<
RATES

Mike               {{{1/5}}}
Ronald             {{{1/x}}}
Both Together     {{{1/5+1/x}}}
</pre>
RT=J uniform rates rule to connect rate, time, amount of job.


One-third of an hour Mike worked alone; three hours the two worked together; one whole job done.

{{{highlight_green((1/5)(1/3)+(1/5+1/x)*3=1)}}}


{{{x+3*3x+3*15=15x}}}


{{{10x+45=15x}}}


{{{45=5x}}}


{{{x=45/5=9}}}, as you were asking.  YES.