Question

The sum of the two digits of a number is 9. If the tens digit is one-half the units digit, what is the number? Let t = the tens digit, u = the units digit, and t + u = 9. Which of the following equations would complete the system?

Answer 1

Answer:t=$\frac{u}{2}$

Step-by-step explanation:

First equation t+u=9

Second equation t = $\frac{u}{2}$ since the number in the tens position is one half of the one in the units. So if you divide u by two, you should have one t, as the equation states

Answer 2

The second condition tells you that $t$ is half the size of $u$, so $t=\dfrac12u$, which could be rewritten in several ways. In standard form, that would be $2t-u=0$.