Rico invests some of his savings at 3 percent per year & an equal amount at 5 percent per year. His income totals 1,800 a year. How much did Rico invest at each rate?

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Answer 1 · 2017-02-17T18:14:50

#$22,500" "# at each rate.

The interest is earned over one year, so it does not matter whether it is invested at simple or compound interest.

Let the amount of money at each rate be #x#

#SI = (PRT)/100#

#(x xx 3 xx 1)/100 + (x xx 5xx 1)/100 = 1800#

Multiply by 100 to cancel the denominators.

#(color(blue)(100xx)x xx 3 xx 1)/100 + (color(blue)(100xx)x xx 5xx 1)/100 = color(blue)(100xx)1800#

#3x +5x = 180,000#

#8x = 180,000)

#x =$22,500#