Question 190513
Let {{{1/12}}}=amount of work Jim does in 1 minute
.   {{{1/18}}}=amount of work Bob does in 1 minute
.   {{{1/x}}}=amount of work both Jim and Bob does in 1 minute
.   x=number of minutes Jim and Bob will do the work
.
{{{(1/12)+(1/18)=(1/x)}}}
.
Multiply both sides by x:
.
{{{(1/12)*x+(1/18)*x=(1/x)*x}}}
{{{(x/12)+(x/18)=1}}}
.
Multiply both sides by 36(GCF):
.
{{{(x/12)*36+(x/18)*36=1*36}}}
{{{3x+2x=36}}}
{{{5x=36}}}
.
dividing both sides by 5:
.
{{{5x/5=36/5}}}
{{{x=7.2}}}
.
It will take Jim and Bob 7.2 minutes to the job together