1/10 and 3/30
0.35
That is 45%.
0.65
9/10
It is: 13/20 = 26/40
2 and 4/5ths is the same as 2 and 16/20ths. 1 and 1/4th is the same as 1 and 5/20ths. So if you add 2 and 16/20ths to 1 and 5/20ths you get 3 and 21/20ths which is the same as 4 and 1/20th.
2.1
4/20 = 1/5 or 0.2
5/20 = 1/4.
2/5ths = 4/10ths = 8/20ths = 16/40ths = 20/50ths = 40/100ths
9/10, 36/40/ 180/200