So you add all the like terms.......i.e numbers with same variable
so,
5x+9y-7x+2-5y-7x+2-3x
=(5-7-7-3)x+(9-5)y+2+2
=-12x+4y+4

- A common unit of measurement for water's density is gram per milliliter (1 g/ml) or 1 gram per cubic centimeter (1 g/cm3). Actually, the exact density of water is not really 1 g/ml, but rather a bit less (very, very little less), at 0.9998395 g/ml at 4.0° Celsius (39.2° Fahrenheit).
- Water density changes with temperature and salinity. Density is measured as mass (g) per unit of volume (cm³). Water is densest at 3.98°C and is least dense at 0°C (freezing point). Water density changes with temperature and salinity.
- When water is a liquid, the water molecules are packed relatively close together but can slide past each other and move around freely (as stated earlier, that makes it a liquid). Pure water has a density of 1.000 g/cm3 at 4˚ C. As the temperature increases or decreases from 4˚ C, the density of water decreases.
Step-by-step explanation:

9 = 4
18 = 8
27 = 12
36 = 16
45 = 20
Answer:
x = 3
Step-by-step explanation:
40+ 46x + 2 = 180 degrees
46x = 180 - 42
x = 3
30 * 0.05 + 1 = X
1.5 + 1 = X
2.5 = X
The light remains yellow for 2.5 seconds on a street with a speed limit of 30.