3/8 is smaller than 3/5
Find the LCD of both fractions:
Multiples of 8:
8, 16, 24, 32, 40, 48, 56, 64, 72, …
Multiples of 5:
5, 10, 15, 20, 25, 30, 35, 40, 45, …
40 is the LCD of denominators 5 and 8.
Multiply both denominators by a number that makes it 40, multiply that same number by each numerator:
3/8:
3 x 5 = 15
8 x 5 = 40
15/40
3/5:
3 x 8 = 24
5 x 8 = 40
24/40
15/40 < 24/40
Hope this helps