[tex] \frac{61/2}{20} = \frac{x}{81/8}[/tex] multiply the 2nd fraction by 8/8 to get rid of the 8 in the denominator: [tex]\frac{61/2}{20} = \frac{8x}{81}[/tex] simplify the 1st fraction by multiplying by 2/2: [tex]\frac{61}{40} = \frac{8x}{81}[/tex] now, you can cross-multiply: [tex]61*81=40*8x[/tex] [tex]4941=320x[/tex] [tex]x=\frac{4941}{320}[/tex] or [tex]15 \frac{141}{320}[/tex]
