how do you do proportions

Question

I am doing math work and I am stuck on proportions.

Answer 1

I suggest that you can (1) learn from a good textbook (2) learn by Googling proportions. There should be lots of stuff to view online via Youtube.

 

One thing is to learn how to set them up; another thing is to know how to solve equations of that type, when one of the quantities is unknown.

 

Here's a brief mini-lesson.  If a/b = c/d, then the PRODUCT OF THE MEANS EQUALS THE PRODUCT OF THE EXTREMES. This gives us bc = ad.

 

You can invert each side, giving b/a = d/c.

 

You can do denominator addition: (a+b)/b = (c+d)/d.

 

Proportions are used in problems such as determining distance between cities when you have a map, a ruler and the map's scale factor.

 

In Geometry, corresponding parts of similar figures are in proportion; this will be used a great deal when you get into the Geometry course.