Expert: Sherry Wallin - 7/26/2010

Question
Hello,

I have 2 question regarding equations systems solutions


1 - Solve each system by the addition method.

3/7 x + 5/9 y = 27
1/9 x + 2/7 y = 7


2-

3 x - 2.5 y = 7.125
2.5 x - 3 y = 7.3125

Answer
Khalid~
    What are the questions? These are problems to be worked out and I don't have a clue what it is about them that you don't understand. But for starters in both you can make it much easier by getting rid of the fractions and decimals:

1- 63(3/7 x + 5/9 Y = 27) -> 27x + 35y = 1701  -> this is the new system you can use to find
    63(1/9 x + 2/7 y = 7) ->   7x + 18y = 441          the solution using either the method of  
                                                                             elimination or addition

2- 1000(3x - 2.5y = 7.125) ->      3000x -  2500y = 7125    this is your 'new' system
    10000(2.5x - 3y = 7.3125) -> 25000x - 30000y = 73125

Note: for #1 I found the least common denominator (LCD) and the LCD = 63 and multiplied each equation by 63 to get rid of the fractions.  For #2 in the first equation I needed to multiply by 1000 to get 7.125 to become a whole number and in the second equation I needed to multiply .3125 by 10000 to get it to become a whole number.

Math Prof