The answer would be C (P=T/2). This can be explained by examining the ratio. If you were to put in the answer of T = 12, then you would be looking for T/2 or 6, assuming we're giving them each half of the amount original held by grandmother.
6 teams 5 times the key word is times this means multiply so 6x5=30
11:100
iwan:siobhan
if iwan gets 11% then iwan gets 89/100