Answer: One DVD is $12 and one book is $1
Step-by-step explanation:
Let the DVD be d and the book be b.
Case 1:
3d + 4b = $40.......(1)
Case 2:
1d + 6b = $18........... (2)
In this equations above, I intend to eliminate variable d, so I'm going to multiply the coefficient of d in (1) to multiply (2)
3 × (1d + 6b = 18)
3d + 18b = 54........ .(3)
Then, subtract (1) from (3)
3d + 18b = 54
- ( 3d + 4b = 40)
3d - 3d + 18b - 4b = 54 - 40
0 + 14b = 14
b = 14/14
b = 1.
Then substitute 1 for b in (2)
1d + 6(1) = 18
d + 6 = 18
d = 18 - 6
d = 12.
(d,b) = (12,1)
First question is 1:2
Second question is 12
R^2π=500in^2
r^2=500 in^2/π
r=(500 in^2/π)^(1/2)= 12.62 in
plug it in:
db=3da=3(2(12.62))= 75.69
r of b = 75.69/2=37.85in
A of b = (37.85in)^2π = 8.22 in^2
Answer:
18
Step-by-step explanation:
3+9=12
12/2=6
6x3=18
Answer:
21kg
Step-by-step explanation:
We will do this.
11x - 12 = 7x
11x - 4x = 7x
4x = 12
4x/4 = 12/4
x = 3
3 x 7 = 21
Laura weighs 21 kg.
