Răspuns :
=70·6=420
a1+a2+a3=60·3=180
a4+a5+a6=420-180=240
(a4+a5+a6)÷3=240÷3=80
a1+a2+a3=60·3=180
a4+a5+a6=420-180=240
(a4+a5+a6)÷3=240÷3=80
a + b+ c + d + e + f = 70 * 6 = 420
a + b + c = 60 * 3 = 180
420 - 180 = 240
d + e + f = 240
a + b + c = 60 * 3 = 180
420 - 180 = 240
d + e + f = 240