can yhelp me with my homework please i'm desperate for your help =[

Question

my math class is after an hour helpp plzzzzzzzzzz !! answer these thanks! find the second propotion of 2,4,6 find the third propotion of 8,6,12 if a/b = 3/5 find the value of 7a+9b : 4a+2b answer plzzzzzzzzzzzz and an explanation would be more than awesome :D ‏