What does it mean find an equivalent fraction for each fraction 20/100

It means to find a fraction that is the same for example 2/3 is equal to 4/6 these two fractions are equivalent.

Either simplify 20/100 to get something equivalent or multiply the numerator and the denominator by the same number to get an equivalent fraction. In example, 20/2 is 10. 100/2 is 50

20/100=10/50

You can then do 10/5 and 50/5 to get 20/100=2/10

If you simplify more, 2/10=1/5

If you multiply numerator and denominator by the same number if would look like this: 20/100*2/2=40/200