2*( - 7 15 - 2 3 ) - 11 21 : 5 7

"/" - знак деления (дроби).2×(-715-23)-1121÷57 = 2×(-738)-1121÷57 = -1476-1121÷57 = -1476-59/3 = -(4428+59) / 3 = -4487 / 3 = -1495 2/3.