Select the best possible first step to solving the system by first eliminating the x variable.

3x + 5y = 1
2x + 4y = −4

The best possible first step would be to multiply equation one by 4 and equation by 5 that would eliminate the y and allow you to solve for x.

In essence,      4 × (3x  +  5y = 1)   eq1
                        5 × (2x + 4y = -4)    eq2
 
   thus giving rise to  12x + 20y = 4     eq1 × 4
                                  10x +20y = -20  eq2 × 5

You can then just subtract one equation from the other
For example,   (12x + 20y = 4) - ( 10x +20y = -20 ) 

                        12x - 10x + 20y - 20y = 4 - (-20) 
                                                      2x = 24
                                                        x = 12