Question

5/4 to 3/8 as a percent change

Answer 1

Well, what's the diffrence from 5/4 to 3/8?

$\bf \cfrac{5}{4}-\cfrac{3}{8}\qquad \stackrel{\textit{LCD is 8 clearly}}{\implies }\qquad \cfrac{10-3}{8}\implies \cfrac{7}{8}$

so, if we take 5/4 to be the 100%, what is 7/8 off of it in percentage anyway?

$\bf \begin{array}{ccll} amount&\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ \frac{5}{4}&100\\\\ \frac{7}{8}&x \end{array}\implies \cfrac{\quad \frac{5}{4}\quad }{\frac{7}{8}}=\cfrac{100}{x}\implies \cfrac{5}{4}\cdot \cfrac{8}{7}=\cfrac{100}{x} \\\\\\ \cfrac{40}{28}=\cfrac{100}{x}\implies x=\cfrac{28\cdot 100}{40}$