Răspuns :
841+5x[9600:30-ax(54:9)]=1991
5x[9600:30-ax(54:9)]=1991 - 841
5×(320 - a× 6) = 1 150
320 - a × 6 = 1 150 : 5
320 - a × 6 = 230
a × 6 = 320 - 230
a × 6 = 90
a = 90 : 6
a = 15
5x[9600:30-ax(54:9)]=1991 - 841
5×(320 - a× 6) = 1 150
320 - a × 6 = 1 150 : 5
320 - a × 6 = 230
a × 6 = 320 - 230
a × 6 = 90
a = 90 : 6
a = 15