How to Add and Subtract Units of Measure
We are already familiar with the concept of addition and subtraction of normal numbers. However, as we move to measure units, the method becomes more customized. It would help if you always remembered that only the same kinds of units could be added or subtracted. In other words, you cannot add two chairs and three tables together. You can only add 2 chairs and 3 chairs to make them 5 chairs. In many cases, you will need to convert units of measure to the same system and exact denomination within that system. Once you have completed that it is only a matter of processing the operations. You just need to pay attention to the subunits of measurement system to make sure that they units do not denature some where along the way. The best way to approach this is act like the difference between denominations are place values and then carry on.
These problems are all set up as if you working in construction and completed a project that require a set value of supplies. You need to calculate how many more you would need based on the multiplier that is presented to you.