Question

Patru carti si cinci pixuri costa 60 lei , iar 12 carti si 7 pixuri costa 148 lei . Cat costa 28 de pixuri?

Answer 1

$Notam~ cu ~c = carte$
$Notam ~cu~ p= pix$
$4 c + 5p = 60$
$12c + 7p = 148$
$12c + 15p = 180$
$12c + 7p = 148$
$8p = 32$
$p = 32 : 8$
$p = 4$
$4c + 5 * 4 = 60$
$4c = 60 - 20$
$4c = 40$
$c=40:4$
$c = 10$
$28 * 4 = 112 ~lei~ costa ~28 ~pixuri$