Answer:
p - 0.2p = p(1 - 0.2) = p(0.8) = 0.8p
p + 0.2p = p(1 + 0.2) = p(1.2) = 1.2p
p + (1/4)p = p(1 + 1/4) = p(5/4) = (5/4)p
p - (1/4)p = p(1 - 1/4) = p(3/4) = (3/4)p
Hope this helps!