2×{17+14:[27-(15+a)]-3}=45-3
2×{17+14:[27-(15+a)]-3}= 42
17+14:[27-(15+a)]-3= 42÷2
17+14:[27-(15+a)]-3= 21
14:[27-(15+a)]-3=21-17
14:[27-(15+a)]-3= 4
14:[27-(15+a)]=4+3
14:[27-(15+a)]=7
27-(15+a)= 14÷7
27-(15+a)= 2
15+a=27-2
15+a=25
a=25-15
a=10
Sper că e corect...
