Răspuns :
(a- 5·6+ 10·5): 5+ 4·8=42
(a- 30+50): 5+ 4·8=42
(a- 30+50): 5+ 32=42
(a- 30+50): 5 = 42-32
(a- 30+50): 5 = 10
(a- 30+50) = 10·5
a- 30+50 = 50
a--30 = 50- 50
a - 30 = 0
a = 0+ 30
a =30
(a- 30+50): 5+ 4·8=42
(a- 30+50): 5+ 32=42
(a- 30+50): 5 = 42-32
(a- 30+50): 5 = 10
(a- 30+50) = 10·5
a- 30+50 = 50
a--30 = 50- 50
a - 30 = 0
a = 0+ 30
a =30