Question 1152573
r, the rate for one worker
n, the number of extra friends to help


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Four workers are building a house. In five days they built half the house. But
winter is coming and they want to finish building the house in two more days.
How many friends should the workers call for help?
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{{{4r*5=1/2}}}
AND
{{{(4+n)r*2=1/2}}}