Together, Betty and Bill picked 15 + 12 = <<15+12=27>>27 oranges.
Frank picked 3 * 27 = <<3*27=81>>81 oranges.
Frank planted 2 * 81 = <<2*81=162>>162 seeds in total, so there are 162 orange trees 20 years later.
Philip can then pick 162 * 5 = <<162*5=810>>810 oranges.
#### 810