SOLUTION: Hi. How can I solve this? Thanks. Both Mr Gan and Mr Koon received a salary every month. Last month, Mr Gan's salary was 9/10 of Mr Koon's salary. This month, Mr Gan's salary decr

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: Hi. How can I solve this? Thanks. Both Mr Gan and Mr Koon received a salary every month. Last month, Mr Gan's salary was 9/10 of Mr Koon's salary. This month, Mr Gan's salary decr      Log On


   



Question 1201373: Hi. How can I solve this? Thanks.
Both Mr Gan and Mr Koon received a salary every month. Last month, Mr Gan's salary was 9/10 of Mr Koon's salary. This month, Mr Gan's salary decreased by $220 while Mr Koon's salary increased by $200. In the end, Mr Gan's salary was 7/10 of Mr Koon's salary. What was Mr Gan's salary last month?

Found 3 solutions by josgarithmetic, MathTherapy, greenestamps:
Answer by josgarithmetic(39620) About Me  (Show Source):
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              Lastmonth          Thismonth

Gan            0.9k              0.9k-220

Koon            k                 k+200

"In the end" must mean, "This Month".

0.9k-220=%287%2F10%29%28k%2B200%29----------literally according to the description.
.
.
Use found k to evaluate 0.9k.

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
Hi. How can I solve this? Thanks.
Both Mr Gan and Mr Koon received a salary every month. Last month, Mr Gan's salary was 9/10 of Mr Koon's salary. This month, Mr Gan's salary decreased by $220 while Mr Koon's salary increased by $200. In the end, Mr Gan's salary was 7/10 of Mr Koon's salary. What was Mr Gan's salary last month?

Let Gan's salary, last month, be G
Since last month, Mr Gan's salary was 9%2F10 of Mr Koon's salary, Mr. Koon's salary, last month, was matrix%281%2C3%2C+%2810%2F9%29G%2C+%22=%22%2C+10G%2F9%29
With Gan's salary decreasing by $220, Gan's salary, this month, is G - 220.
With Koon's salary increasing by $200, Koon's salary, this month = 10G%2F9+%2B+200

As Gan's salary, this month, was 7%2F10 of Koon's, this month, we get:  
                                                                 9(G - 220) = 7G + 140(9) ------ Cross-multiplying
                                                                9G - 220(9) = 7G + 140(9)
                                                                    9G - 7G = 140(9) + 220(9)
                                                                         2G = (140 + 220)(9)
                                                                         2G = 360(9)
                                 Mr. Gan's salary, last month, or 

Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


You CAN solve the problem using fractions or decimals, as shown in responses from other tutors. But the actual work to solve the problem is usually easier if we can set the problem up using whole numbers.

Since last month Mr Gan's salary was 9/10 of Mr Koon's salary...

let 9x = Mr. Gan's salary last month
let 10x = Mr. Koon's salary last month

When Mr. Gan's salary decreased by $220 and Mr. Koon's salary increased by $200, Mr. Gan's new salary was 7/10 of Mr Koon's new salary:

%289x-220%29%2F%2810x%2B200%29=7%2F10
7%2810x%2B200%29=10%289x-220%29
70x%2B1400=90x-2200
3600=20x
x=180

ANSWER: Mr. Gan's salary last month was 9x = 9($180) = $1620