Verdict. The Microsoft Lumia 638 is an attractive budget friendly smartphone with the latest Windows OS and support for 4G LTE Cat4. It features a powerful Qualcomm Snapdragon processor but the lack of front camera is a big disappointment.
Steps. 1. Make sure that the denominators of every fraction that you're going to add or subtract are the same. 1  If the numbers are different, you can't add or subtract the fractions as-is.2  You can, however, perform the operations necessary to create fractions with like denominators, in which case you can add and subtract them.teps. 1. Make sure that the denominators of every fraction that you're going to add or subtract are the same. 1  If the numbers are different, you can't add or subtract the fractions as-is.
1. Find an equivalent fraction where the denominator is a power of ten. You can do this by either multiplying or reducing the fraction. If your fraction already contains a denominator that is a power of ten, skip this step.2. Compare the number of digits in the numerator to that of the denominator.