Answer:
Step-by-step explanation:
[tex]\dfrac{15}{y}=\dfrac{40:4}{12:4}\\\\\dfrac{15}{y}=\dfrac{10}{3}\qquad\text{cross multiply}\\\\10y=(15)(3)\\\\10y=45\qquad\text{divide both sides by 10}\\\\\dfrac{10y}{10}=\dfrac{45}{10}\\\\y=4.5[/tex]
