(19n-6n)÷4=26 (16m+5m)÷18=7 (17n-8n)×13=351

(19п-6п):4=26; 13п=26*4; 13п=104; п=104:13; п=8

(16м+5м):18=7; 21м=18*7; 21м=126; м=126:21; м=6

(17п-8п)*13=351; 9п=351:13; 9п=27; п=27:9; п=3

1) (19n-6n)÷4=26
13n÷4=26
13n=26×4
13n=104
n=104÷13
n=8
2)(16m+5m)÷18=7
21m÷18=7
21m=18×7
21m=126
m=126÷21
m=6
3)(17n-8n)×13=351
9n=351÷13
9n=27
n=27÷9
n=3