Name: Tim Kirkpatrick
Level: 10th Grade Algebra
Who: Parent
Problem:
The ratio of W to H was 7 to 9. The ratio of H to I was 9 to 5. If the sum of the W and H exceeded twice the number of I by 12, how many were W, how were H and how many were I?
I have tried substitution, using the equalities below, replacing variables W & I with the corresponding values containing variable H. The problem with this is I end up with a negative sign for the H term after moving them all to the left, because of multiplying by 2.
I don't know if I'm approaching this right or have the correct equalities set up.
I have:
7W = 9H. (So W = 9H/7)?
9H = 5I. (So I = 9H/5)? And 5I = 7W?
Used formula of H + W = 2(I) + 12
Thanks, Tim
Tim, you need to be a bit more careful at the start:
W is to H as 7 is to 9 means W/H = 7/9 not 7W = 9H etc. Redo your second ratio also and get W in terms of I which you then can use with your W+H = 2I+12.
Penny