Home > CC2MN > Chapter 1 > Lesson 1.1.2 > Problem 1-15
Maria was playing a game with her brother. She said, “I’m thinking of a number. When you multiply my number by six and add seven, you get twenty-five. What is my number?”
Find Maria’s number.
How big do you expect her number to be? Can you think of a reasonable number to try?
Pick a reasonable number and try Maria's steps. Let's try
. If Maria multiplies this number ( ) by , she would get . Then, adding , she would get . Can you think of a number that might work better? Try it!
Since
is smaller than , let's choose a bigger number. Let's try . If Maria multiplies by , she would get . Adding , she would get . Since Maria gets by using this number, is the number she described. We now know that Maria's number is
. Explain how you figured out your answer to Maria’s number puzzle.
Can you describe with words the steps that you took to find Maria's number?