The number of red roses Lorelei picks is 12 x 50% = <<12*50*.01=6>>6 roses.
The number of pink roses Lorelei picks is 18 x 50% = <<18*50*.01=9>>9 roses.
The number of yellow roses she picks is 20 x 25% = <<20*25*.01=5>>5 roses.
The number of orange roses she picks is 8 x 25% = <<8*25*.01=2>>2 roses.
The total number of roses in her vase is 6 + 9 + 5 + 2 = <<6+9+5+2=22>>22 roses.
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