9514 1404 393
Answer:
-3
Step-by-step explanation:
The coefficients of the x-terms are (-3, -7). If you swap them, you have (-7, -3). Negating one of them will give you (7, -3) or (-7, 3). Either of these pairs of multipliers will work to eliminate the x-terms.
The problem statement tells us the multiplier of the first equation is 7, so the multiplier of the second equation needs to be -3.