Algebra 1HardSystems of Equations ShareSystems of Equations · Hard problemHow many solutions does this system have?{−x−7y=10−3x−21y=30\begin{cases} - x - 7 y = 10 \\ - 3 x - 21 y = 30 \end{cases}{−x−7y=10−3x−21y=30Ainfinitely many solutionsBexactly one solutionCno solutionCheck Show answer Walk through it step by step Practice more like this Review this concept