Formula for compound interest is
Interest = Amount - Principal
Interest = 
- P
Where r = rate in percent
t = time in years
For Jaina,
P = $300
r= 7%
t = 3 yrs
So, Interest = 
- 300
For Tomas
P = $400
r= 4%
t = 3 yrs
So, Interest = 
- 400
So pair of equations for Jaina and Tomas are
Interest = - 300
Interest = - 400
The volume of the box without the lid is 500 cubic inches.
<h3>What is volume?</h3>
The capacity of an object is measured by its volume. For instance, a cup's capacity is stated to be 100 ml if it can hold 100 ml of water in its brim.
Another way to think of volume is as the amount of space a three-dimensional object takes up.
Calculation for the volume of the box-
The volume of a box without a lid is given by the formula v = 4x(10-x)².
Where,
'x' is a length in inches, and
'v' is the volume in cubic inches.
The volume when x = 5 inches.
Substitute the value of 'x' in the formula of volume;
v = 4×5(10-5)²
= 20×5²
v = 500
Therefore, the volume of a box without a lid is 500 cubic inches.
To know more about the volume of a cardboard shoe box, here
brainly.com/question/623789
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To solve the problem w must know about the Associative property.
<h2>Associative property</h2>
The associative property states that the addition of the sum of two numbers (a,b) and a third number(c) is equal to the addition of the sun of the last two numbers(b, c) and the first number(a).
The property that will allow Carmen to do this without changing the value of the expression is the Associative property.
<h2>Explanation</h2>
Given to us
<h3>Associative property.</h3>
Now, using Associative property,
(6.21 + 0.93 ) + 0.07
= 6.21 + (0.93 + 0.07)
=6.21 + (0.93 + 0.07)
Hence, the property that will allow Carmen to do this without changing the value of the expression is the Associative property.
Learn more about Associative property:
brainly.com/question/1680548
The answer for this problem is 26.
