How do you do this , i need help!!

112º

Step-by-step explanation:

(you may need a calculator for this)

first let's start with what we know, we know a triangle has 180º. We also know a line has 180º. if you know the line has 180º, then ? + 126 º = 180º. so if you subtract 126 from 180, you get 54. now lets look at the triangle, we know the triangle has 180º in total. we already know one angle is 58º, and we just figured out the other is 54º. if you do 54+58, you get 112. remember, the triangle has 180 degrees in total, and two of them equal 112º, so 180 - 112 is 68. almost there! now we have to do the line trick again, because on the line, 68 + x = 180. 180- 68 is 112, so the answer is 112º. Hope this helps :D

51

step-by-step explanation:

73-22=51 the   mass number minus the amount of protons gives you the amount of neutrons

24

step-by-step explanation: