21) What negative effect did the introduction of rice have on the New World?

\[ \left\{\begin{array}{c}2 x+y-3 z=1 \\ -x+y-4 z=-2 \\ x+\frac{1}{2} Y-\frac{3}{2} z=\frac{1}{2}\end{array} \quad \text { b) }\left\{\begin{array}{c}2 x-y-z=2 \\ -x+y-z=1 \\ 2 x-y-z=-3\end{array} \quad \text { c) }\left\{\begin{array}{l}2 x+y-z=1 \\ x-2 y+2 z=3 \\ 3 x-2 y+z=2\end{array}\right.\right.\right. \] igna: Representarlos gráficamente usando Geogebra 3D. Luego, indicar de conjunto solución tienen. Y por último, clasificarlos.

Solve this system of equations \( \left\{\begin{array}{l}-4 x-3 y=-4 \\ x+3 y=10\end{array}\right. \) \( x=\square \) \( y=\square \)

Equation of Line A: \( y-4=-(x-2) \) Graph of Line B:

What happens in chapter 14 of The Lightning Thief that convers this same theme? A. Percy is visited by the woman in the river. B. Percy gets back on the train to Denver. C. Percy is alone at the bottom of the river. D. Percy is identified on the news as a fugitive.

\( 11+.241=\_ \) Type your answer here.