Question

№568
10k-k=702

4 l+5 l+l=1200

6t+3t-t=6400

Answer 1

10k-k=702
9k=702
k=702/9
k=78

4i+5i+i=1200
9i+i=1200
10i=1200
i=1200/10
i=120

6t+3t-t=6400
9t-t=6400
8t=6400
t=6400/8
t=800