let temperature_data = [ [60.2, 61.2, 63.4, 64.8, 65.1, 63.2, 62.9], [62.5, 63.8, 63.4, 64.6, 65.8, 64.9, 65.0], [63.4, 64.5, 65.2, 64.8, 65.1, 64.9, 66.2], [66.3, 66.8, 66.4, 66.8, 67.8, 67.9, 68.2] ]; for (i = 0; i < 4; i++) { let length = temperature_data[i].length; let weeklySum = 0; for (j = 0; j < length; j++) { weeklySum += temperature_data[i][j]; } console.log("Week " + i + " Average Temperature: " + (weeklySum / 7)); }