Phyllis invested 51000 dollars, a portion earning a simple interest rate of 4 percent per year and the rest earning a rate of 7 percent per year. After one year the total interest earned on these investments was 2370 dollars. How much money did she invest at each rate?

Phyllis invested $11,000 at a simple interest rate of 7 percent per year and $40,000 at a simple interest rate of 4 percent per year.

Step-by-step explanation:

From the information provided, you can write the following equations:

x+y=51000 (1)

0.04x+0.07y=2370 (2), where

x is the portion earning a simple interest rate of 4 percent per year

y is the portion earning a simple interest rate of 7 percent per year

First, you can isolate x in (1):

x=51000-y (3)

Now, you can replace (3) in (2) and solve for y:

0.04(51000-y)+0.07y=2370

2040-0.04y+0.07y=2370

0.03y=330

y=330/0.03

y=11000

Then, you can replace the value of y in (3) to find the value of x:

x=51000-11000

x=40000

According to this, the answer is that Phyllis invested $11,000 at a simple interest rate of 7 percent per year and $40,000 at a simple interest rate of 4 percent per year.

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step-by-step explanation: