Answer:
Therefore solution for a is

Step-by-step explanation:
Given:
7a - 2b = 5a + b
To Find:
a = ?
Solution:
7a - 2b = 5a + b .................Given
First take all the 'a' terms to the left hand side and 'b' terms to the right-hand side of the equation,
∴ 
Now dividing by 2 on both the side we get
∴ 
Therefore solution for a is

X=12*(21/14)=18 // you can find the ratio of the according sides.
-》D
Answer:
b
Step-by-step explanation:
we have
------> equation 
------> equation 
Multiply by
the equation 
------> equation 
Sum equation
and equation 

Substitute the value of x in the equation 

therefore
the answer is the option B
