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Video: Using Substitution to Determine Whether a Given Number Makes an Equation or Inequality True

Kathryn Kingham

Identify which of the list {43, 44, 45} is the solution of 𝑡 ÷ 3 = 15.

01:51

Video Transcript

Identify which of the list 43, 44, 45 is the solution of 𝑡 divided by three equals 15.

We’ve been given an equation and then a set of numbers to check for a solution. We’ll use substitution here and substitute 43, 44, 45 in for 𝑡. This will help us determine which of the variables make the statement true.

Let’s start with 43. We need to know does 43 divided by three equal 15. 43 divided by three equals 14.3 repeating, which is not 15. This tells us that 𝑡 is not equal to 43.

We’ll solve the problem again, this time substituting 44 for 𝑡. We wanna know does 44 divided by three equal 15. 44 divided by three equals 14.6 repeating, which is not 15. And 44 will also not be our solution for 𝑡.

Finally, we can substitute 45 for 𝑡. Does 45 divided by three equal 15? It does. 45 divided by three equals 15. That means that 𝑡 equals 45. By using substitution, we eliminated all the other possible answers and found that 𝑡 was equal to 45.