Równanie:
[tex]12(3-8x)-9(8-9x) = 11(12-7x)-8(1-9x)\\36+(-96x)+(-72)+81x = 132+(-77x)+(-8)+72x\\-15x-36 = -5x+124/+5x\\-10x-36 = 124/+36\\-10x = 160/:(-10)\\x = -16[/tex]
Zadanie z posągiem:
Cyna stanowi:
[tex]100\% - 78\% = 22\%[/tex]
Więc [tex]22\% = 660kg[/tex]
[tex]22\% - 660kg\\78\% - x\\\\x = \frac{78\% \cdot 660}{22\%} = \frac{78\cdot660}{22} = \frac{51,480}{22} = 2,340kg[/tex]
Odp: Potrzeba 2340kg miedzi.