6x3+8x2-2x+4=30-2x
10x3+x2+11x+9=21+13x
Answer:
11
Step-by-step explanation:





The value of two arithmetic means which are inserted between 3 and 24 are 24/9 and 75/9.
<h3>What is arithmetic mean?</h3>
Arithmetic mean is the mean or average which is equal to the ratio of sum of all the group numbers to the total numbers.
The two arithmetic means between 3 and 24 are has to be inserted.
3, A₂, A₃, 24
All the four numbers are in arithmetic progression. The nth terms of AM can be found using the following formula:
t(n)=a(n-1)d
Here, d is the common difference a is the first terms and n is the total term. The first term, a=3 and t₄=24. Thus, the common difference is;

The second and 3rd term are:

Thus, the value of two arithmetic means which are inserted between 3 and 24 are 24/9 and 75/9.
Learn more about the arithmetic mean here;
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Answer:
Step-by-step explanation:
let x = the amount of money in the second piggy back
We assume that the second piggy bank has MORE than the piggy bank with $7.31 in it:
x - 7.31 ≤ 10
<u>Solution</u>
Add 7.31 to both sides: x - 7.31 + 7.31 ≤ 10 + 7.31
⇒ x ≤ 17.31
Answer: 40 %
Step-by-step explanation:
Let the amount of one card = x
Hence, the value of 20 cards ( Principal amount ) = 20x
And, the value of 22 cards ( Total amount after 3 month ) = 22x
⇒ Total interest in 3 month = 22x - 20x =2x
Let the annual interest rate = r %
( By the formula of simple interest rate )




Hence, the annual rate of interest = 40%