Question

Trei kilograme de piersici si patru kilograme de caise costa 36,50 lei, iar sase kilograme de piersici si sapte kilograme de caise costa 67,25 de lei. Cat costa un kilogram de piersici ? Dar unul de caise ?

Answer 1

$\left\{\begin{matrix} 3p + 4c = 36.50 \: | \times ( - 2)\\ 6p + 7c = 67.25\end{matrix}\right.$

$\left\{\begin{matrix} - 6p - 8c = - 73\\ 6p + 7c = 67.25\end{matrix}\right.$

$- 6p + 6p - 8c + 7c = - 73 + 67.25$

$- c = - 5.75 \: | \times ( - 1)$

$c = 5.75 \: lei$

$3p + 4c = 36.50$

$3p + 4 \times 5.75 = 36.50$

$3p + 23 = 36.50$

$3p = 36.50 - 23$

$3p = 13.5$

$p = 13.5 \div 3$

$p = 4.5 \: lei$