Răspuns :
1225 : [(13 × a - 30 ) : 3 - 10 ] = 7
(13 × a - 30 ) : 3 - 10 = 1 225 : 7
(13 × a - 30 ) : 3 - 10 = 175
(13 × a - 30 ) : 3 = 175 + 10
(13 × a - 30 ) : 3 = 185
13 × a - 30 = 185 x 3
13 × a - 30 = 555
13 × a = 555 + 30
a = 585 : 13
a = 45
(13 × a - 30 ) : 3 - 10 = 1 225 : 7
(13 × a - 30 ) : 3 - 10 = 175
(13 × a - 30 ) : 3 = 175 + 10
(13 × a - 30 ) : 3 = 185
13 × a - 30 = 185 x 3
13 × a - 30 = 555
13 × a = 555 + 30
a = 585 : 13
a = 45
1225 : [(13 × a - 30 ) : 3 - 10 ] = 7
(13 × a - 30 ) : 3 - 10 = 1 225 : 7
(13 × a - 30 ) : 3 - 10 = 175
(13 × a - 30 ) : 3 = 175 + 10
(13 × a - 30 ) : 3 = 185
13 × a - 30 = 185 x 3
13 × a - 30 = 555
13 × a = 555 + 30
a = 585 : 13
a = 45
(13 × a - 30 ) : 3 - 10 = 1 225 : 7
(13 × a - 30 ) : 3 - 10 = 175
(13 × a - 30 ) : 3 = 175 + 10
(13 × a - 30 ) : 3 = 185
13 × a - 30 = 185 x 3
13 × a - 30 = 555
13 × a = 555 + 30
a = 585 : 13
a = 45