Răspuns :
3ca+5cr=247 /×2
6ca+10cr=494
2ca=3cr /×3
6ca=9cr
(inlocuim):
9cr+10cr=494
19cr=494
cr=26
2ca=3cr
2ca=26×3
2ca=78
ca=39
6ca+10cr=494
2ca=3cr /×3
6ca=9cr
(inlocuim):
9cr+10cr=494
19cr=494
cr=26
2ca=3cr
2ca=26×3
2ca=78
ca=39