b. [tex] \left \{ {{x+2y=3} \atop {0,2x-3,5y=4}} \right. = \left \{ {{x=3-2y} \atop {0,2(3-2y)-3,5y=4}} \right.= \left \{ {x=3-2y} \atop {0,6-0,4y-3,5y=4}} \right. = \left \{ {{x=3-2y} \atop {0,6-3,9y=4}} \right.= [/tex]
[tex] \left \{ {x=3-2y} \atop {-3,9y=4-0,6}} \right.= \left \{ {{x=3-2y} \atop {-3,9y=3,4}} \right.= \left \{ {{x=3-2y} \atop {y=-0,87}} \right.= \left \{ {{x=3+1,74} \atop {y=-0,87}} \right.= \left \{ {{x=4,74} \atop {y=-0,87}} \right. [/tex]