Step 1
Define the terms in the given function
[tex]y=(\frac{a}{a+b})(y_2-y_{1_{}})+y_1[/tex]Where
[tex]\begin{gathered} a=5 \\ b=2 \\ y_2=3 \\ y_1=1 \end{gathered}[/tex]Step 2
Substitute and get the required formula
[tex]\begin{gathered} (\frac{5}{2+5})(3-1)+1 \\ (\frac{5}{7})(3-1)+1 \end{gathered}[/tex]Hence option 3 is right