900-у*90=90 450+с\8=500 7200\д+3100=4000

Question

900-у*90=90 450+с\8=500 7200\д+3100=4000

Answer 1

900-у*90=90

у*90=90+900

у=990/90

у=11

450+с\8=500

с/8=500-450

с/8=50

с=50*8

с=400

7200\д+3100=4000

7200/д=4000-3100

7200/д=900

д=7200/900

д=8