(19n-6n):4=26 (16m+5m):18=7 (17n-8n)•13=351
1. (19n-6n):4=26 13n:4=26 13n=26×4 13n=104 n= 104:13 n=8 (13×8):4=26 104:4=26 26=26 2. (16m+5m):18=7 21m=7×18 21m=126 m= 126:21 m=6 (21×6):18=7 126:18=7 7=7 3. (17n+8n)×13=351 25n=351:13 25n=27 n=27:25 n=1,08 (25×1,08 )×13=351 27×13=351 351=351