Answer:

see the procedure
Step-by-step explanation:
we have

Solve for a
That means ---> isolate the variable a
Subtract c both sides


Divide by b both sides


Answer: Option C
, 
Step-by-step explanation:
If the lines m and n are parallel then the large triangle and the small triangle are similar triangles, because they have equal angles.
By definition for similar triangles it is satisfied that if they have sides of length a, b, c and a ', b' and c 'then:

In this case

So:




Therefore
if
and
then 
Finally
, 
Answer:
-1 ≤ x ≤8 (don't care about the equal sign)
Step-by-step explanation:
-6+4≤2x≤12+4
=-2≤2x≤16
=-1≤x≤8