Performance 66764

Six masons of equal performance were able to plaster the walls of the new garages in 18 shifts. After 4 shifts of joint plastering, 2 got sick.
a) In how many more shifts did the masons complete the said plastering?
b) In how many shifts was the assigned task completely completed?

Correct answer:

x =  21
y =  25

Step-by-step explanation:

$$\begin{gathered} n=6 \\ 18\cdot n=4\cdot n+x\cdot (n-2) \\ 18\cdot 6=4\cdot 6+x\cdot (6-2) \\ 4x=84 \\ x=\frac{84}{4}=21 \\ x=21 \end{gathered}$$

$y=4+x=4+21=25$

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