Question

the pair of polygons is similar. find the value of x. answer on picture

Answer 1

30/75 = 12/x
30*x=75*12
30x=900/:30
x=30

Answer 2

$30\ in - 75\ in\\ 12\ in - x\ in\\ \\ 30x=75\cdot 12\\ 30x=900\ /:30\\ x=30\ in$