Solution: If the hummingbird weighs X grams, the sparrow weighs X+79.4 grams.
x+x+79.4=82.6
2x+79.4=82.6
2x=82.6-79.4
2x=3.2
x= 1.6
Sparrow weight x+79.4 =1.6+79.4 = 81g.
The ocean area on the earth's surface is about 2.4 times of the land area, which is 2 1 100 million square kilometers more than the land area. How many billion square kilometers are there in the ocean area and the mainland area?
Solution: If the land area is X billion square kilometers, the ocean area is 2.4x million square kilometers.
2.4x-x=2. 1
1.4x=2. 1
x= 1.5
The ocean area is 2.4x =1.5x2.4 = 360 million square kilometers.
There are the same number of chickens and rabbits in the cage, with 48 legs. How many chickens and rabbits are there in each cage?
Solution: Suppose there are X chickens and rabbits in each cage.
2x+4x=48
6x=48
x=8