a painter and his son can paint a room together in 8 hrs. if the father works aloe for 3 hours and then is joined by his son, the two together can complete the job in 6 hours. how long will it take each person alone to paint the room ?

Question

amistre64 · Answer

3f + 3(f+s) = 6

f+s = 8

is what i read from the jargon

amistre64 · Answer

3f + 3(f+s) = 6
f+s = 8


3f+3f+3s = 6
f+s = 8


6f+3s = 6
  f +s = 8


  6f+3s = 6
-3f -3s =-24
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 3f        = -18

         f = -6

-6 + s = 8

         s = 14


doesnt make a whole lot of sense tho

amistre64 · Answer

maybe 8(f+s) = 8  but im sure this is the wrong way to go about it :/

amistre64 · Answer

8hrs * (f+s) = 1 job

f+s = 1/8 job per hour

3hrs*f + 3*(f+s) = 1 job

f + 1/8 = 1/3

f = 1/3 - 1/8 = 5jobs/24hrs; or 1job in 24/5 hrs

amistre64 · Answer

sounds good, but still doesnt make sense to me quite right

amistre64 · Answer

f + f + f + 1/8 + 1/8 + 1/8 = done

it took 3 hours to do 3/8 of the room; which means the father did 5/8 of it in 3 hours by himself.  5/8 divided by 3 = 5/24ths in an hour ...

anonymous · Answer

@amistre64 how come my friend got father=12 son=24 ?

amistre64 · Answer

dunno, youd have to ask your friend :)  im not even sure if my thought was correct.

amistre64 · Answer

i know the f+s is good; since working together they can do 1/8 of the job in an hour

3 hours working alone, 3 hours working with son = 6 hours 

makes sense to me, but it would appear that the son actually slows things down if im right