Question

3 acadele si 5 ciocolate - Ionică a platit 27 lei
3 acadele si 3 ciocolate-Ionica a platit 18 lei
Cit costa o ciocolata?
Cit costa o acadea?
URGENT VA ROG FRUMOS!!!

Answer 1

$\left\{\begin{matrix} 3a + 5c = 27\\ 3a + 3c = 18 \: | \times ( - 1)\end{matrix}\right.$

$\left\{\begin{matrix} 3a + 5c = 27\\ - 3a - 3c = - 18\end{matrix}\right.$

$3a - 3a + 5c - 3c = 27 - 18$

$2c = 9$

$c = \frac{9}{2}$

$c = 4.5 \: lei$

$3a + 5c = 27$

$3a + 5 \times 4.5 = 27$

$3a + 22.5 = 27$

$3a = 27 - 22.5$

$3a = 4.5$

$a = \frac{4.5}{3}$

$a = 1.5 \: lei$