Question

4kg de rosii si 5 kg de castraveti costa 8,80 lei , iar 7 kg de castraveti si 4 kg de rosii costa 10,40 lei.
a) cat costa un kg de castraveti
b) cate kg de rosii si cate kg de castraveti ( exprimate prin nr naturale nenule) se pot cumpara cu 7,20lei?

Answer 1

$\left \{ {{4x+5y=8,80} \atop {4x+7y=10,4}} \right.$ ⇔$\left \{ {{4x=8,80-5y} \atop {2y=1,60}} \right.$ ⇔$\left \{ {{4x=4,80} \atop {y=0,80}} \right.$ ⇔$\left \{ {{x=1,20} \atop {y=0,8}} \right.$