Answer :
[tex]3=a\cdot1+b\\
5=a\cdot2+b\\\\
b=3-a\\
2a+b=5\\\\
2a+3-a=5\\
a=2\\\\
b=3-2\\
b=1\\\\
y=2x+1 \Rightarrow B[/tex]
[tex](1,3) ,\ \ (2,5) \\ \\ \\ First \ find \ the \ slope \ of \ the \ line \ thru \ the \ points \: \\ \\ m= \frac{y_{2}-y_{1}}{x_{2}-x_{1} } \\ \\m=\frac{5-3}{2-1} = \frac{2}{1}=2 \\ \\Now \ use \ y = mx + b \ with \ either \ point \ to \ find \ b, \ the \ y-intercept \ : \\ \\ y=mx+b \\ \\3=2 \cdot 1+b\\ \\3= 2 +b \\ \\b=3-2=1 \\ \\ y=2x+1 \ is \ the \ answer \ B[/tex]
