(a+109)*30=6510
d-(240*13)=1260
(a+109)*30=6510 а+109=6510/30
а+109=217
а=217-109
а=108
проверка:
(108+109)*30=6510
217*30=6510
6510=6510 d-(240*13)=1260
d- 3120=1260
d=1260+3120
d=4380
4380-(240*13)=1260
4380- 3120=1260
1260=1260
1. (a+109)*30=6510
a+109=6510:30
a+109=217
a=217-109
a=108
2. d-(240*13)=1260
d-1260=240*13
d-1260=3120