Ok I can help you on number 5 and 6. Sorry I dont understand number 7. You are correct on number six. There is not enough information because they do not say how many are 12 and how many are younger than 12. So on number 5 you would take 67 and divide it by 5. That is 13.4 so your answer for number 5 would be 13.4. Hope this helps!

**Answer: -6x^2 + 3 and 1 - 4x^2**

**Step-by-step explanation:**

A quadratic expression is an expression that can be in the form ax^2 + bx + c, where a, b, and c are all constants, and a does not equal 0. (ax must be squared, it can't be raised to a power other than 2)

-6x^2 + 3 and 1 - 4x^2 can be in the form ax^2 + bx + c. Therefore, they are the quadratic expressions.

<h2>

**Answer:**</h2>

<em><u>**Distance for which Aeroplane can be in contact with Airport B is =**</u></em> <em><u>**396.34 km**</u></em>

<h2>

**Step-by-step explanation:**</h2>

In the question,

We have an Airport at point A and another at point B.

Now,

Airplane flying at the angle of 72° with vertical catches signals from point D.

Distance travelled by Airplane, **AD = 495 km
**

Now, Let us say,

**AB = x
**

So,

In triangle ABD, **Using Cosine Rule**, we get,

So,

On putting the values, we get,

Therefore, x is given by,

**
x = 212.696, 728.844**

So,

The value of x can not be 212.696 as the length of LB (radius) itself is 300 km.

So,

**x = 728.844 km**

So,

**AL = AB - BL**

AL = x - 300

AL = 728.844 - 300

**AL = 428.844 km**

Now, in the circle from a <u>**property of secants**</u> we can say that,

<u>**AL x AM = AD x AC**</u>

So,

428.844 x (728.844 + 300) = 495 x AC

441213.576 = 495 x AC

<u>**AC = 891.34 km**</u>

So,

<em>**The value of CD is given by,**</em>

CD = AC - AD

CD = 891.34 - 495

<u>**CD = 396.34 km**</u>

<em><u>**Therefore, the distance for which the Aeroplane can still be in the contact with Airport B is 396.34 km.**</u></em>

<span>You know that you need to rename a mixed Number to subtract when the numbers involved have different denominators. In such a case, the lowest common multiple (LCM) of the denominators must be calculated and subsequently used to adequately rename the mixed numbers before subtraction can be done.</span>