no, i mow 400 yards for 30$ each yard, I mow 1 time a week every week for 4 months. how much will I have if I split it 50/50 with my sister

If you mow 400 yards for $30 each yard, your total earnings per week will be 400 * $30 = $<<400*30=12000>>12,000.

Since you mow 1 time a week every week for 4 months, you will earn a total of 4 * 12 = <<4*12=48>>48 times in those four months.
So, your total earnings for those four months will be 48 * $12,000 = $<<48*12000=576000>>576,000.
If you split your earnings 50/50 with your sister, you would each receive $576,000 / 2 = $<<576000/2=288000>>288,000.