Data return from Multiple Activities to Main Activity

everyone. I have started to write(1-month-old) Android apps and I am pretty new this stuff.

I have a activity X. On that activity X, I have four different buttons calls four different activities. On those three activities, I have button, and I am returning data to activity X after I pressed button. Also, on the activity X, I may not call all three of the activies. I might call just 1,3 or just 2,3. I have looked a lot but I could not find what I seek for.

EDIT: when I put finish();to activity 1,2,3, I could call one of the activies(assume activity one called) and able to grab data, and returns the Activity X, but when I started to call other one (assumed activity 2 called), I could go to this activity, but I cannot return from it since it does know where to return.

This is what I seek for:

Activity X-> 1st activity -> return data1 to X

Activity X-> 2nd activity -> return data2 to X

Activity X-> 3rd activity -> return data3 to X

Activity X-> send data1 + data2 +data3 to 4th activity

I started my three activities on Activity X like this under onClick method (data_global is global on Activity X class)

case R.id.btn1:
       Intent i = new Intent(this, Activity1.class);
       startActivityForResult(i, 200);
       break;
case R.id.btn2:
       i = new Intent(this, Activity2.class);
       startActivityForResult(i, 201);
       break;
case R.id.btn3:
       i = new Intent(this, Activity3.class);
       startActivityForResult(i, 202);
       break;
case R.id.btn4:
       i = new Intent(this, Activity4.class);
       i.putExtra("Extra", data_global);
       startActivity(i);
       break;

I take my data from here on Activity X under onActivityResult method:

switch (requestCode) {
        case (200): {
            if (resultCode == Activity.RESULT_OK) {
                if (data.getStringExtra("Extra1").length() != 0) {
                    data_global += data.getStringExtra("Extra1");
                }
            }
            break;
        }
        case (201): {
            if (resultCode == Activity.RESULT_OK) {
                if (data.getStringExtra("Extra2").length() != 0) {
                    data_global += data.getStringExtra("Extra2");
                }
            }
            break;
        }
        case (202): {
            if (resultCode == Activity.RESULT_OK) {
                if (data.getStringExtra("Extra3").length() != 0) {
                    data_global += data.getStringExtra("Extra3");
                }
            }
            break;
        }

And any of activity 1 or 2 or 3 code is like that:(X is at the end on Extra referring to 1,2,3)

case R.id.btnSave:
            Intent resultIntent = new Intent();
            resultIntent.putExtra("ExtraX", "name");
            setResult(Activity.RESULT_OK, resultIntent);
            finish();
            break;

How can I solve my problem? Many thanks.