Question 1110376
4 skilled workers rate, {{{4R*5=1}}}, {{{R=1/20}}}----rate for 1 skilled worker


5 semi-skilled workers,  {{{5r*6=1}}}, {{{r=1/30}}}----rate for 1 semi-skilled worker


How long for 1 semi-skilled and 2 skilled workers working together?
Their collective work rate is {{{2(1/20)+1(1/30)}}}

{{{1/10+1/30}}}


{{{3/30+1/30}}}


{{{4/30}}}


{{{2/15}}}----------JOBS per DAYS


In DAYS per 1 JOB, this is {{{15/2=highlight(7&1/2)}}} days.