Frame image

Peter wants to put a picture in a frame. The picture is 7 3/5 cm wide, and it cannot be wider than 7 3/10 cm to fit in the frame. How much should the image be trimmed?

Correct answer:

x =  3/20 cm

Step-by-step explanation:

$$\begin{gathered} a=7\frac{3}{5}=7+\frac{3}{5}=\frac{7\cdot 5+3}{5}=\frac{35+3}{5}=\frac{38}{5}=7.6\text{cm} \\ b=7\frac{3}{10}=7+\frac{3}{10}=\frac{7\cdot 10+3}{10}=\frac{70+3}{10}=\frac{73}{10}=7.3\text{cm} \\ x=(a-b)/2=(\frac{38}{5}-\frac{73}{10})/2=\frac{3}{20}\text{cm}=0.15\text{cm} \end{gathered}$$

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