Răspuns:
4k +15-8-21= 22
4k= 22+21+8-15
4k= 36
k= 36/4
k= 9
k×4+15-24:3-21=22
k×4+15-8-21=22
k×4+15-8=22+21
k×4+15-8=43
k×4+15=43+8
k×4+15=51
k×4=51-15
k×4=36
k=36:4
k=9