Răspuns :
12 per. sandale + 18 per.pantofi ......... 3120 lei I x 5
10 per. sandale + 25 per.pantofi ......... 3800 lei I x 6 =>
60 per. sandale + 90 per.pantofi ......... 15600 lei (₁ )
60 per. sandale + 150 per.pantofi .........22800 lei (₂)
(₂)-(₁) = 60 per. pantofi = 22800-15600 = 7200 lei
1 per. pantofi = 7200:60 = 120 lei
10 per.sandale + 25x120 ---------- 3800 lei ...............(25x120=3000)
10 per.sandale = 3800-3000 = 800 lei =>
1 per.sandale = 800:10 = 80 lei
7 per. sandale + 7 per.pantofi = 7x 80 + 7 x 120 = 560+840 = 1400 lei