Question

求解一道数学题，用一元一次方程解答

Mrs jones invests $4000 for 10% yearly profit and $6000 at 12%yearly profit .how much should she invest at 15%profit so that her total yearly profit is 13%of the total amount she has invest?

Answer 1

jones 存了4000美元，年利率10%，存了6000美元，年利率12%
问：她要存多少钱，年利率为15%，才能使总的年利率为13%
解：设年利率15%的需要存x元
4000×10%+6000×12%+15%*x=（4000+6000+x）×13%
1120+0.15x=1300+0.13x
0.15x-0.13x=1300-1120
0.02x=180
x=9000
答：。。。

Answer 2

设总投资量为X
4000 x 10% + 6000 x 15% +(X-10000)15%=13%X
解得X=19000 需要的投资量为19000-10000=9000
希望对你有帮助

Answer 3

Suppose Mrs Jones should invest $x at 15% profit.
Then 4000*10%+6000*12%+x*15% = (4000+6000+x)*13%
so x = 9000

Answer 4

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