Answer:
easy
Step-by-step explanation:
21-11=10
10:2=5
X= rad 13^2-5^2= 169-25=144=12
X=12
3 - x = 9 <em>subtract 3 from both sides</em>
3 - 3 - x = 9 - 3
-x = 6 <em>change the signs</em>
x = -6