application problem

Question

The ratio of red and blue marbles is 2:3. There are 550 marbles altogether. How many are red? I have to write an equation and solve.

Answer 1

Dear Liz,

      2:3    means  2/3   There are two red marbles for every 3 blue marbles.

 

2X= number of red marbles

3X= number of blue marbles

                                                                                                       

 

Altogether  means  "total."  However, if you have 550 total,  then you need to find the number of red.

 

Question:  How many are red?

 

2X  + 3X  =  550                   Collect terms by adding the "X's."

 

5X= 550                Divide by the number next to "X."

 

X=550/5  =

 

2X=___________How many red marbles?

 

It is also good to check your equation 2X +3X= 550 to see if it is true.  Just substitute value of "X" into it.