Digital primer

Proceed. Read me what you have written down."
"Let _x_ equal the number of rods he built each day," began Fifi
bravely.
"Proceed."
"Then _105_ divided by _x_ equals number of days consumed. And _105_
divided by _x - 2_ equals number of days consumed, if he had built _2_
rods less a day."
"Of course."
"And (_105_ / _x - 2_) + _6_ = number of days consumed if it had taken
him six days longer."
"Nothing of the sort."
Fifi coughed. "I don't see why, exactly."
"When the text says 'six days longer,' it means longer than what?"
"Why--longer than ever."
"Doubtless. But you must state it in terms of the problem."
"In terms of the problem," murmured Fifi, her red-brown head bowed over
the bewildering book--"in terms of the problem."
"Of course," said her teacher, "there is but one thing which longer can
mean; that is longer than the original rate of progress. Yet you add the
six to the time required under the new rate of progress."
"I--I'm really afraid I don't quite see. I'm dreadfully stupid, I
know--"
"Take it this way then. You have set down here two facts.


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