Find perimeter in cm of the diagram

3 sides of square is 3*12=36 cm

perimeter for the full circle is 2 * pi * radius

which is =2 * 22/7 * 12 =75.43 cm

so 360° =75.43 cm

for 150° = 75.43/360 *150 =31.43

all together =36 +31.43 =67.43 cm

the sum of all the angles in a triangle are equal to 180

so you can add   the 3 given angles together to equal 180:

5y + 2y + 2y = 180

or since all three angles have the same letter, combine the 3 angles to equal 180:

9y = 180