Chapter 1 - Foundations for Algebra - 1-8 An Introduction to Equations - Practice and Problem-Solving Exercises - Page 56: 30

y=3

This question involves mental math. There is a negative in front of the y, so doing it the traditional way is a bit difficult to do in our head. Thus, we ask ourselves 7 minus what number equals 4. We know that 4+3 is 7, so thus we remember that 7 minus 3 is 4, meaning that y=3.