fidawka11 (х+15)-8=17
х+15=17+8
х+15=25
х=10

(10+15)-8=17
25-8=17.


(24+х)-21=10
24+х=10+21
24+х=31
х=31-24
х=7

(24+7)-21=10
31-21=10



(45-у)+18=58
45-у=58-18
45-у=40
у=5


(45-5)+18=58
40+18=58