According to the meaning and known, there are:
(x+40)× 16+24x=8640
16x+640+24x=8640
8x=800
x= 100(m？ /h)
Excavation of the second excavator: 100×24=2400(m? )
Excavation of the first excavator: 8640-2400=6240(m? )
A: The first one dug 2,400 cubic meters, and the second one dug 6,240 cubic meters.
2. Solution: Let the price of each color TV set be X yuan.
According to the meaning and known, there are:
10×[( 1+40%)x×80%-x]= 2700
0. 12x=270
X=2250 (yuan)
A: The original price of each color TV set is 2250 yuan.
2. Solution: The standard monthly water consumption of a family of three is X cubic meters.
According to the meaning and known, there are:
1.3x+2.9( 12-x)=22
1.3x+34.8-2.9x=22
1.6x= 12.8
X=8 (m3)
A: The standard monthly water consumption of a family of three in this city is 8 cubic meters.