School attendance percentage

In 5 A class today, there were four pupils, and in 5B, there were two pupils. What percentage of Fridays was in school if 21 pupils attend 5 A and 5B is six pupils more?

Final Answer:

p =  87.5 %

Step-by-step explanation:

$$\begin{gathered} a=21 \\ b=21+6=27 \\ x=(a-4)+(b-2)=(21-4)+(27-2)=42 \\ y=a+b=21+27=48 \\ p=100\cdot \frac{x}{y}=100\cdot \frac{42}{48}=\frac{100\cdot 42}{48}=\frac{4200}{48}=\frac{175}{2}\%=87.5\% \end{gathered}$$

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