You have 100 to bet across two matches with known win probabilities and posted odds. How do you split it, and how much do you hold back?

Match A is Pink against Maroon, and Pink wins with probability 40%. Match B is Brown against Cyan, and Brown wins with probability 70%. The odds offered, as winnings to stake, are Pink 7:4, Maroon 2:3, Brown 1:4 and Cyan 3:1. Both matches are played at the same time. You may bet whole amounts up to 100 in total and you need not bet it all. The prompt says there is no single correct answer but many wrong ones.