multiplying A1 by 0 and adding it to A2, we will get B2
multiplying [A2] by 1, we get [B2]
multiplying A2 by 2 and adding it to A1, we get B1
Here, we want to understand how we can transform the equations to one another
Firstly, we want to know what will make equation [A1] tranform into [B1]
From the image;
[A1] is -5x-4y = 9
B1 is 13x = 39
There is no way to multiply a number by A1 to give B1
Secondly, we want to transform [A2] to [B2]
[A2] is 9x + 2y = 15
[B2] is 9x + 2y = 15
We can see that both are the same thing
So by multiplying [A2] by 1, we get [B2]
So, what we fill in the blank would be 1
Thirdly;
we want to get [B2] from [A1] and [A2] addition
B2 is 9x+2y = 15
A1 is -5x-4y = 9
A2 is 9x + 2y = 15
So, by multiplying A1 by 0 and adding it to A2, we will get B2
For the fourth;
We want to get B1 from A2 and A1
B1 is 13x = 39
A2 is 9x + 2y = 15
A1 is -5x-4y= 9
So by multiplying A2 by 2 and adding it to A1, we get B1
Mathematically, that would be;
2(9x+2y=15) + (-5x-4y=9)
18x+ 4y = 30 + -5x-4y=9
That would give 13x = 39 which is B2