Math Help!?MATH!?Math for the quick!?

I really need your help comrades! I am about to take the entrance test for college and now reviewing. Hope you aid me by solving these questions and stating your reasons for the solution. Thank You! Please don't get bored answering the following:

1. A dealer wishes to mix 30 kg of nuts which cost Php 90 per kg, with some more expensive nuts which cost Php 120 per kg, in order to make a mixture that will cost Php 100 per kg. How many kg of the more expensive nuts should he use?

a. 10
b. 15
c. 20
d. 25

2. If the diameter of a circle is increased by 20% by how many percent is its area increased?

a. 20
b. 21
c. 40
d. 44

3. A rectangular box is 16 cm long, 12 cm wide and 8 cm high. How many cubes with a 4 cm edge can it contain?

a. 24
b. 16
c. 12
d. 10

4. Bruce lives 8 meters south of the church while Wayne lives east of the church. Wayne finds that the direct distance from his house to Bruce鈥檚 is 6 meters shorter than the distance by the way of the church. What is the distance (m) between their houses?

a. 5 square root of 2
b. 17
c. 13
d. 6 square root of 2

5. A man is 12 meters away from one road and 9 meters away from another road. The two roads intersect perpendicularly. How many meters is he from the intersection?

a. 16
b. 9 square root of 2
c. 15
d. 12 square root of 2

Answer :
Answer 1. Let the expensive nuts to be mixed be x Kg
Therefore:
(30*90 + 120*x) / (x+30) =100

-> x= 15 g
Answer 2:
If the diameter is increased by 20%, therefore, radius is also increased by 20%.
lets say, initial Area be a1 and initial radius be r1 and Final after incremented by 20% be A2 and r2 respectely.
r2=1.2r1
-> A2/A1= 1.2*1.2 *r*r /(r*r)
-> Area Increased by 44%
Answer (d)

Answer 3)
Number of Cubed: Volume of cuboid/ volume of cube
= 16*12*8/(4*4*4)=24 Cubes
Answer a:

answer 4:)
Let the diastance between Wayne's House and church be x metres;
There
(x+8)-sqrt(x2 + 64)= 6
x=15

we need is distance between the hiouse which is (sqrt)(x2+ 64) = 17

Answer 5)
Its a right angled triangle with sides equivalent to 9 and 12, therefore the third side is square root of the sum of the squares of the other two= 13

Do your homework dude.

u expect us to do this for u? man im 13