Answer: 16y² - x²
Step-by-step explanation: The - sign means a difference, so the choices with + signs are eliminated (though 64x² and 9 are squares)
10 is not a square so that one is eliminated (though the y² and the 4x² are squares)
16 is the square of 4, y² is the square of y, and x² is the square. That expression shows a difference of squares.
Given:
The rate of interest on three accounts are 7%, 8%, 9%.
She has twice as much money invested at 8% as she does in 7%.
She has three times as much at 9% as she has at 7%.
Total interest for the year is $150.
To find:
Amount invested on each rate.
Solution:
Let x be the amount invested at 7%. Then,
The amount invested at 8% = 2x
The amount invested at 9% = 3x
Total interest for the year is $150.

Multiply both sides by 100.


Divide both sides by 50.


The amount invested at 7% is
.
The amount invested at 8% is

The amount invested at 9% is

Thus, the stockbroker invested $300 at 7%, $600 at 8%, and $900 at 9%.
Answer:
18
Step-by-step explanation: