having trouble understanding this.

Answer:
x=142 degrees
Step-by-step explanation:
we know that a triangle adds up to 180 degrees, so we know 2 angles already which are 90 and 52 so we subtract them
180-90-52= 38
so 38 is the missing angle and we need to find the angle outside so we subtract 38 from 180
180-38= 142
so x=142
The square that you see at the bottom means 90 degrees
The outside angle (in this case "x") is equal to 90 + 52 which is 142 degrees