Let the number be x. We need [tex]\frac{17-x}{23-x}=5/8[/tex] Cross multiply: [tex]8(17-x)=5(23-x)[/tex] Expand: [tex]136-8x=115-5x[/tex] Simplify: [tex]3x=126-115[/tex] [tex]x=21/3=7[/tex]
Check: [tex]\frac{17-7}{23-7}=\frac{10}{16}=\frac{5}{8}[/tex] ok
