We need a common denominator to see the larger fraction here. 40 will do. Change the fractions by a form of one.
8*2/8*5 = 16/40
5*2/5*8 = 10/40
So , 2/5 is greater than 2/8
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2/5 and 2/8 which one is greater than?
Any two fractions, A/B and C/D can be compared by computing the following: B*C and A*D
If BC < AD, ---> A/B > C/D
So compare 2/5 and 2/8
B*C = 5*2 = 10
A*D = 2*8 = 16
10 < 16, so 2/5 > 2/8