math
posted by es on .
I asked this question but no one answered it. Can someone please help explain this before I have my math test today. THANKS.
A carpenter has several boards of equal length. He cuts 3/5 of each board. After cutting the boards the carpenter noticies he has enough pieces left to make up the same length as 4 origional boards. How many origional boards did he start with?
Someone told me the answer is 10 but I do not understand how they got it. I would like to know how to do the question, so can you explain the steps.
Thanks

Let the number of boards he had be x
So the number of pieces he has left over is (2/5)x
So he wants to have 4 lengths or 4x created by these (2/5)x's
(2/5)x > 4 * (2/20)x > 4x * (1/10)
or
4x รท ((2/5)x)
= 4x * ((5/2)(1/x))
= 10