(Scroll down for photo of question) I will give brainliest to correct answer

Shapes A and B are similar.
a) Calculate the scale factor from shape A to shape B.
b) Find the value of w.
Give each answer as an integer or as a fraction in its simplest form.
4 cm
7 cm
3 cm
A
12 cm
B
9 cm
ш ст
Not drawn accurately