3t..................5l......................35lei x5
5t..................7l.......................53 lei x3
15t................25l...................=175
15t.................21l..................=159
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-------- + 4. =16
1. 16:4=4
2. 3t+4x5=35
4. 3t+20=35
5. 3t=35-20
6. 3t=15
7. 1t=15:3
8. 1t=5
R:1t=5,1l=4