2.20 is equivalent to (50)% of 40, 40 is (200 )% of 20, and the number exceeding 20% is (24).
3. An oil mill used 250kg rapeseed to extract 2 15kg oil, and the oil yield of rapeseed was (86 )%.
4. The original price of an air conditioner was 2 100 yuan, which was sold in 300 yuan during the National Day. The price of this air conditioner was reduced by (14.3)%.
5. The radii of the two circles are 5cm and 3cm respectively, the diameter ratio is 5:3, the perimeter ratio is 5:3 and the area ratio is 25:9.
6. Circle a circular iron ring with a length of 12.56 decimeter (excluding the joint). The radius of the iron ring is (2) decimeter and the area is (12.56) square decimeter.
7.9 ÷ ( 12) = 0.75 = (6): 8 = ( 16) 12=( 75 )%.
13/4 ÷ 2+30x12.5% =13/8+30 *1/8 = 43/8 (this topic is probably mistaken, because I guess from the following questions).
40% x 13+87x 0.4 = 0.4 * 13+87 * 0.4 =( 13+87)* 0.4 = 100 * 0.4 = 40
0.32 x78 %+ 1.32 x22 % = 0.32 * 78%+( 1+0.32)* 22% = 0.32 *(78%+22%)+22% = 0.32+0.22 = 0.54
(4/5-3/4+7/ 10)x 100% =(8/ 10+7/ 10-3/4)* 1 = 1.5-0.75 = 0.75 = 3/4
(Solving equation) (Need process)
60%x+25=40
60%x=40-25= 15
x= 15/60%=25
3/4x-5%x= 17.5
0.75x-0.05x= 17.5
0.7x= 17.5
x= 17.5/0.7=25
50%x-33%x=34
0.5x-0.33x=34
0. 17x=34
x=200
120x-20x=40
100x=40
x=0.4