Sorry I could not go to school to teach today, as I had two important campaign events to go to.

As some of you know, I am running for Lexington Housing Authority and Town Meeting Member this time and the election day is coming Tuesday 3/6. This weekend is the last weenend before the election.

So, if you are a Lexington resident, I hope you will go out to vote on Tuesday and vote for me.

That said, here is the material covered today by a substitute teacher:

Section 11.1 on Ratio and Propertion, two important properties to remember:

1. Reciprocal Property: if a/b = c/d, then b/a = d/c if they exist

2. Cross Product Property: if a/b = c/d, then ad = bc

Section 11.2 on Percents: number being compared to base = percent of base number

Section 11.3 on Direct and Inverse Variation:

The variables x and y vary directly if for a constant k, y/x = k or y = kx, k not equal to 0.

The variables x and y vary inversely if for a constant k, xy = k, or y = k/x, k not euqal to 0.

Here is the homework:

http://blog.newtonchineseschool.org/wangweidong/files/2012/03/Math7_Spring_HW_L4.pdf