Answer:
C. 30
Step-by-step explanation:
Distance formula - [tex]\sqrt{(x_{2}-x_{1})^2+(y_{2}-y_{1})^2}[/tex]
The scale factor of 7 is basically saying that the coordinates (3,4) are going to be increased 7 times.
3•7 = 21=x --> A prime = (21,28)
4•7 = 28=y
[tex]\sqrt{(21-3)^2+(28-4)^2}[/tex]
= [tex]\sqrt{324+676}[/tex]
= [tex]\sqrt{900}[/tex]
= 30
