Question

problema.Doua kilograme de pere costa cit rei kilograme de mere.Maria a cumparat un kilogram de mere si un kiloram de pere.achitind suma de 10 lei.determinati preul unui kilogram de pere."

Answer 1

Fie x- 1kg de mere, y-1 kg de pere
$\left \{ {{2y=3x} \atop {x+y=10}} = \left \{ {{2y=3x} \atop {y=10-x}} \right. = \left \{ {{2(10-x)=3x} \atop {y=10-x}} \right. = \left \{ {{20-2x=3x} \atop {y=10-x}} \right. = \left \{ {{-2x-3x=-20} \atop {y=10-x}} \right.$ $\left \{ {{-5x=-20} \atop {y=10-x}} \right. = \left \{ {{x=4} \atop {y=10-4}} \right. = \left \{ {{x=4} \atop {y=6}} \right.$                           
  Raspuns: 4 lei un kg de mere, 6 lei un kg de pere