С=3а b=a-6.8 a+(a-6.8)+3a=43.2 a+a-6.8+3a=43.2 5a-6.8=43.2 5a=43.2+6.8 5a=50 a=10 b=10-6.8=3.2 c=3*10=30 V=abc=10*3.2*30=960 см³