In order to combine fractions, they need to have the same denominator.
To figure out what value to make the denominator, find the least common denominator of 4 and 5:
4: 4, 8, 12, 16, <u>20</u>
5: 5, 10, 15, <u>20</u>
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The LCD is 20, so multiply 4/5 by 4/4 and -1/4 by 5/5 to make the denominator = 20
![(\frac{4}{4} )\frac{4}{5} -(\frac{5}{5} )\frac{1}{4} =](https://tex.z-dn.net/?f=%28%5Cfrac%7B4%7D%7B4%7D%20%29%5Cfrac%7B4%7D%7B5%7D%20-%28%5Cfrac%7B5%7D%7B5%7D%20%29%5Cfrac%7B1%7D%7B4%7D%20%3D)
Now combine the fractions
![\frac{16}{20}- \frac{5}{20} =\frac{11}{20}](https://tex.z-dn.net/?f=%5Cfrac%7B16%7D%7B20%7D-%20%5Cfrac%7B5%7D%7B20%7D%20%3D%5Cfrac%7B11%7D%7B20%7D)