What is the value of k?

k = 10

Step-by-step explanation:

∡ZYX = 180° - 115° = 65° (angles in a line add up to 180°)

*∡ stands for angle.

∑ of  ∡Z , Y and X should be equal to 180° (angles in a triangle add up to 180°)

∴ (4k + 5)° + 65° + (6k + 10)° = 180°

10k + 80 = 180

10k = 100

k = 100 ÷ 10 = 10

36

Step-by-step explanation:

A perfect square is a number that is the product of a whole number multiplied by itself.

This said, perfect squares when rooted will give a whole number.

Now, we can root each of these numbers and see which one gives a whole number.

√5=2.236

√8=2.828

√36=6

√44=6.633

As you can see, the only number that gives a whole number is 36, and therefore 36 is the only perfect square.