Answer: 1
Step-by-step explanation:
There are a few ways to do this. One way is to notice that the jump from 5 to 100 is "times 20" (go from right to left across the bottom denominators).
So we must do the same "times 20" type of jump when going across the numerators. If x is the numerator for the right hand side, then we go from x to 20. That must mean x = 1
Put another way, we could have these steps
20/100 = x/5
20*5 = 100*x ... cross multiplication
100 = 100x
100x = 100
x = 100/100 .... dividing both sides by 100
x = 1
We see that the fraction 20/100 reduces fully to 1/5
To go from 1/5 to 20/100, we multiply both parts by 20 (divide both parts by 20 to go in reverse).