Painting classrooms

Martha solicited 3 2/3 liters of paint for the brigade. Their city mayor gave their school another 2 2/5 liters of paint. How many classrooms can be painted if each classroom needs 1 3/7 liters?

Final Answer:

n =  4

Step-by-step explanation:

$$\begin{gathered} M=3\frac{2}{3}=3+\frac{2}{3}=\frac{3\cdot 3+2}{3}=\frac{9+2}{3}=\frac{11}{3}=3\frac{2}{3}\doteq 3.6667\text{l} \\ A=2\frac{2}{5}=2+\frac{2}{5}=\frac{2\cdot 5+2}{5}=\frac{10+2}{5}=\frac{12}{5}=2\frac{2}{5}=2.4\text{l} \\ c=1\frac{3}{7}=1+\frac{3}{7}=\frac{1\cdot 7+3}{7}=\frac{7+3}{7}=\frac{10}{7}=1\frac{3}{7}\doteq 1.4286\text{l} \\ V=M+A=\frac{11}{3}+\frac{12}{5}=\frac{55}{15}+\frac{36}{15}=\frac{55+36}{15}=\frac{91}{15}=6\frac{1}{15}\doteq 6.0667\text{l} \\ {n}_1=V/c=\frac{91}{15}/\frac{10}{7}=\frac{91}{15}:\frac{10}{7}=\frac{91}{15}\cdot \frac{7}{10}=\frac{91\cdot 7}{15\cdot 10}=\frac{637}{150}\doteq 4.2467 \\ n=\lfloor n_1\rfloor =\lfloor 4.2467\rfloor =4 \end{gathered}$$

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