2.a=5b(b is not equal to 0), and the least common multiple of a and b is (a).
3. The small party calls 30 people, and calls 1 person every minute. It took at least (5) minutes to notify everyone. (30 minutes is not right anyway)
4. Every 20 workers need to complete the task of 10 set of board houses every day. How many times can 20 workers complete this batch of board houses in 20 days?
5,3 * 6 = 18, so 3 and 6 are factors and18 is a multiple error.
6. A piece of land is 3/4 hectares, in which 1/4 kinds of soybeans, 1/5 kinds of potatoes and the rest kinds of peanuts. What is the proportion of peanuts planted in this land? 1- 1/4- 1/5= 1 1/20
The decimal unit of 7/8 is (1/588), and there are (7) decimal units in it. Plus (9) prime numbers with the smallest fractional unit.
8. A rectangular fish pond with a length of10m, a width of 8m and a depth of 2m will be built in the park. If the inner wall and bottom of the bath are plastered with cement, each kilogram of cement can be plastered with 0.8 square meters. How many kilograms of cement does a * * need?
( 10 * 8+ 10 * 2 * 2+8 * 2 * 2)* 0.8 = 12 1.6kg。