Answer:
you basically do the same things just backwards 
Step-by-step explanation:
for example 9+9=18    well to double check your work all you do is flip to equation 18-9=9
 
        
             
        
        
        
Answer:
108
Step-by-step explanation:
3 ft. squared is 9 ft. 
9x12=108
 
        
             
        
        
        
Answer:
30 dollars
Step-by-step explanation:
The y-intercept is 15 and the slope is 30
How?
slope = change in y/change in x
 
        
             
        
        
        
M
=
0
O
r
m
=
23
15
Explanation:
1
3
m
+
6
m
−
9
3
m
=
3
m
−
3
4
m
⇒
1
+
6
m
−
9
3
m
=
3
m
−
3
4
m
⇒
−
8
+
6
m
3
m
=
3
m
−
3
4
m
⇒
(
−
8
+
6
m
)
×
4
m
=
(
3
m
−
3
)
×
3
m
⇒
−
32
m
+
24
m
2
=
9
m
2
−
9
m
⇒
−
32
m
+
24
m
2
−
9
m
2
+
9
m
=
0
⇒
15
m
2
−
23
m
=
0
⇒
m
(
15
m
−
23
)
=
0
m
=
0
Or
15
m
−
23
=
0
⇒
15
m
=
23
⇒
m
=
23
15