Help me please please

1. 2. ∠b and ∠y are right angles. 3.? 4.? which two statements are missing in steps 3 and 4? ∠x ≅ ∠c △abc ~ △zyx by the sas similarity theorem. ∠b ≅ ∠y △abc ~ △zyx by the sas similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem.

Compute the standard deviation of the following set of data to the nearest whole number. 10, 10, 15, 20, 25

Suppose m: angle a =77 degrees what is the measure of a complement of a complement of angle a, what is a conclusion you can draw about a complement of a complement of an angle