For two ratios to be equivalent, its means and extremes if multiplied must be equal to each other.
![\begin{gathered} (a)/(b)=(c)/(d) \\ ad=bc \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/loco10hvzkf2z6ig3aub69c2c3rslcbb81.png)
Let's start with Option A.
![\begin{gathered} (4)/(5)=(2)/(2.5) \\ 4*2.5=2*5 \\ 10=10 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/l25pz281a9oeqad7dsw9njfohbtr8iejg2.png)
Since they are equal, then Option A is equivalent to 4/5.
Let's check Option B.
![\begin{gathered} (4)/(5)=(2)/(3) \\ 4*3=2*5 \\ 12\\e10 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/iudxu827sa8yl2454wbl7bccbwjpmjvbql.png)
Let's check Option C.
![\begin{gathered} (4)/(5)=(3)/(3.75) \\ 4*3.75=5*3 \\ 15=15 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/c42ywy3bv4hgc6hsdcsvsxoo0xff8h7mts.png)
Let's check Option D.
![\begin{gathered} (4)/(5)=(7)/(8) \\ 4*8=5*7 \\ 32\\e35 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/ik24jcdmu4ypj02nyp5ite4fao72zht2g1.png)
Let's check Option E.
![\begin{gathered} (4)/(5)=(8)/(10) \\ 4*10=5*8 \\ 40=40 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/fjeixler3lkhn5vsl3ulclruwk2igglr1q.png)
FInally, let's check Option F.
![\begin{gathered} (4)/(5)=(14)/(27.5) \\ 4*27.5=5*14 \\ 110\\e70 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/8deaz9ailjp1bo0177y4fjwgzx3f7xkksp.png)
Hence, only Option A, Option C, and Option E are equivalent to ratio 4/5.