Question

6,7 х (7,9-y) = 28,81

Answer 1

52.93-6.7y=28.81
 -6.7y=28.8-52.93 
y=24.12/6.7 
y=3.6

Answer 2

7,9-у=28,81/6,7
7,9-у=4,3
у=7,9-4,3
у=3,6
6,7*(7,9-3,6)=28,81
28,81=28,81