решите уравнения:10к-к=702 , 4j+5j+j=1200 , 6t+3t-t=6400
10к-к=702
9к=702
к=702:9
к=78
4j+5j+j=1200
10j=1200
j=1200:10
j=120
6t+3t-t=6400
8t=6400
t=6400:8
t=800