Solve each system by substitution. 1) 2x - 6y = 18
x + 3y = -21

2)y = 2x + 7
2x - y = -3

3) -5x + 6y = -9
3x - 4y = 5

4) -x + 7y = 10
y = 5x - 18

5) y = 4x + 8
y = 5x + 10

6) x + 5y = -7
-5x - 4y = 14

7) -21x + 12y = -9
7x - 4y =3

8) y = -4x - 23
y = 4x + 9

The decibel level of sound is 50 db greater on a busy street than in a quiet room where the intensity of sound is watt/m2. the level of sound in the quiet room is db, and the intensity of sound in the busy street is watt/m2. use the formula , where is the sound level in decibels, i is the intensity of sound, and is the smallest sound intensity that can be heard by the human ear (roughly equal to watts/m2).

What can each term of the equation be multiplied by to eliminate the fractions before solving? x – + 2x = + x 2 6 10 12

If (17, 4) is an ordered pair of the inverse of f(x), which of the following is an ordered pair of the function f(x)? a. (17,4) b. (4.17) c. (4,0) d. 0,17)