Exit status 1 'calculateSum' was not declared in this scope

Projects Programming
7

Com3 is being used Com 1, 3, 4 are empty. In addition to that error message I get this:

Problem uploading to board. See https://support.arduino.cc/hc/en-us/sections/360003198300 for suggestions.
processing.app.SerialException: Error opening serial port 'COM3'.
at processing.app.Serial.(Serial.java:152)
at processing.app.Serial.(Serial.java:82)
at processing.app.SerialMonitor$2.(SerialMonitor.java:132)
at processing.app.SerialMonitor.open(SerialMonitor.java:132)
at processing.app.AbstractMonitor.resume(AbstractMonitor.java:132)
at processing.app.Editor.resumeOrCloseSerialMonitor(Editor.java:2126)
at processing.app.Editor.access$1300(Editor.java:116)
at processing.app.Editor$UploadHandler.run(Editor.java:2095)
at java.lang.Thread.run(Thread.java:748)
Caused by: jssc.SerialPortException: Port name - COM3; Method name - openPort(); Exception type - Port busy.
at jssc.SerialPort.openPort(SerialPort.java:164)
at processing.app.Serial.(Serial.java:141)
... 8 more
Error opening serial port 'COM3'.
Error opening serial port 'COM3'. (Port busy)
Error opening serial port 'COM3'. (Port busy)
Error opening serial port 'COM3'. (Port busy)
Error opening serial port 'COM3'. (Port busy)