SOLUTION: How do I solve this proportion problem? 3 over 5 over b equals 8 over 5 I know I need to cross multiply somewhere I'm just not sure where?

Algebra ->  Proportions  -> Lessons -> SOLUTION: How do I solve this proportion problem? 3 over 5 over b equals 8 over 5 I know I need to cross multiply somewhere I'm just not sure where?       Log On


   

Question 189944This question is from textbook
: How do I solve this proportion problem?
3 over 5 over b equals 8 over 5
I know I need to cross multiply somewhere I'm just not sure where? This question is from textbook

Answer by cutepiscean5(19) About Me  (Show Source):
You can put this solution on YOUR website!
we have the equation as:
+%283%2F5%29%2Fb+=+8%2F5+
we know that b can also be written as b over 1, that is b/1.
so the equation becomes;
+%283%2F5%29%2F%28b%2F1%29+=+8%2F5+
we also know the concept of reciprocals that:
+%28a%2Fb%29%2F%28c%2Fd%29+=+%28a%2Fb%29+%2A+%28d%2Fc%29+
so we first we reduce our equation as:
+3%2F5+%2A+1%2Fb+=+8%2F5+
or, +3%2F%285%2Ab%29+=+8%2F5+
now cross multiply, we get:
+3%2A5+=+%285%2Ab%29+%2A+8+
=> +15+=+40%2Ab+
=> +b+=+15%2F40+
=> +b+=+3%2F8+ (in the lowest fraction terms)
so, that's our answer.
Hope this helps you.