7*7 - (7*9 -19 ) +a*4 =29
49 - (63-19) + a*4=29
49-44 + a*4=29
5 +a*4=29
a*4= 29-5
a*4=24
a=24:4
а=6
7*7 - (7*9-19) +6*4 =29
49 - 44 +24 =29
5+24=29
29=29
(8*7 -63:9) :а = 55 - 6*8
(56 - 7):а = 55-48
49:а = 7
а= 49:7
а= 7
(8*7 -63:9) :7 = 55 - 6*8
(56-7) :7 = 55 -48
49:7 = 7
7=7