School bun distribution

There were buns for lunch at school. The freshmen ate one-eighth of the buns. The sophomores ate two-eighths of the buns. Third and fourth graders ate three-eighths. How many eighths of the buns are left for the upper grades?

Final Answer:

x =  1/4

Step-by-step explanation:

$$\begin{gathered} a=\frac{1}{8}+\frac{2}{8}+\frac{3}{8}=\frac{1+2+3}{8}=\frac{6}{8}=\frac{3}{4}=0.75 \\ x=1-a=1-\frac{3}{4}=\frac{1\cdot 4}{4}-\frac{3}{4}=\frac{4}{4}-\frac{3}{4}=\frac{4-3}{4}=\frac{1}{4}=0.25 \end{gathered}$$

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