.
70*x = (70+10)*(x-5) <<<---=== It is what the condition says.
70x = 80*(x-5)
70x = 80x - 400
400 = 80x - 70x
10x = 400 ===========>>> x = 400/10 = 40.
ANSWER. 40 days.
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The info about 3 new hired workers is a) Excessive; b) Unnecessary; c) it is not used in the solution;
and d) it is included to confuse the reader and to distract his attention.