[tex]\dfrac{2\frac{1}{4}}{\frac{3}{8}}=\dfrac{\frac{15}{16}}{x}\ \ \ \ |\text{cross multiply}\\\\2\dfrac{1}{4}x=\dfrac{3}{8}\cdot\dfrac{15}{16}\\\\\dfrac{2\cdot4+1}{4}x=\dfrac{45}{128}\\\\\dfrac{9}{4}x=\dfrac{45}{128}\ \ \ \ \ |\text{multiply both sides by 4}\\\\9x=\dfrac{45}{32}\ \ \ \ \ |\text{divide both sides by 9}\\\\\boxed{x=\dfrac{5}{32}}[/tex]
