I think you meant to say "equivalent" instead of "equipment"
To find equivalent fractions to 3/8, you would multiply top and bottom by the same number.
If we multiply the top and bottom by 5 for instance, then
3*5 = 15
8*5 = 40
So 3/8 is equivalent to 15/40
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Another example: multiply top and bottom by 9
3*9 = 27
8*9 = 72
This means 3/8 is equivalent to 27/72
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Now let's say you were asked if 15/40 was equivalent to 3/8
To check this, you would assume they are equal, then cross multiply like so
15/40 = 3/8
15*8 = 40*3 ... cross multiply
120 = 120
Since we end up with the same thing on both sides, we have confirmed that 15/40 = 3/8 is a true equation.