X=area of Sahara.
y=area of the Gobi Desert.
We suggest this system equations:
x+y=4000000
x=7y
solve by susbstitution method.
(7y)+y=4,000,000
8y=4,000,000
y=4,000,000 / 8=500,000
x=7y
x=7(500,000)=3,500,000
The area of Sahara=3,500,00 miles².
The area of the Gobi Desert=500,000 miles²
To check:
Te sum of their areas is : 3,500,000 miles²+500,000 miles²=4,000,000 miles²
Te area of sahara (3,500,000 miles²) is 7 times the area of the Gobi Desert (7*500,000 miles²=3,500,000 miles²).
1 gal = 3.8 liters....so 65 gallons = 65 * 3.8 = 247 liters
140 / 100 * X = 56
X = 56 * 100 / 140 = 5600 / 140 = 40
6x plus 3x plus 4 minus 2
