From the course: Learning Algebra: Solving Equations
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Solving subtraction equations using decimals
From the course: Learning Algebra: Solving Equations
Solving subtraction equations using decimals
- Our last subtraction equation example is going to involve decimals. This equation, -5.8 = z - 2.5, looks very confusing. Not only does it have decimals, but the problem is also written backwards. There are actually two approaches to solving this problem as well. Some people don't mind working with the equation, even though it's written backwards. In that case, you would simply start on the right-hand side of the equation, instead of the left-hand side. So, we could bring down z - 2.5, and ask ourselves, "What would we do to get rid of the - 2.5?" We need to get z by itself. In order to get rid of - 2.5, we would use the opposite operation, which is to add 2.5. Now, since I added 2.5 to the right-hand side, I now need to go back to the left-hand side, and remember to add 2.5, as well. Now, on the left-hand side, I have -5.8 + 2.5, that equals -3.3, and on the right-hand side, I'm left with just z, because -2.5 + 2.5 is 0, and they cancel out. So, my final answer is -3.3 = z, and that…
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