Răspuns:
a = 4
Explicație pas cu pas:
200 - ( 64 + a x 12 + 4 x 11 ) = 2 x ( 50 - 24 x 2 + 13 x 5 - 9 x 5 )
200 - ( 64 + a x 12 + 44 )= 2 x ( 50 - 48 + 65 - 45 )
200 - ( 64 + a x 12 + 44 ) = 2 x ( 2 + 20 )
200 - ( 64 + a x 12 + 44) = 2 x 22
200 - ( 64 + a x 12 + 44= 44
64 + a x 12 + 44 = 200 - 44
64 + a x 12 + 44 = 156
64 + a x 12 = 156 - 44
64 + a x 12 = 112
a x 12 = 112 - 64
a x 12 = 48
a = 48 : 12
a = 4