Question

1. Ввчислите (30:27-1/3)*2 1/7+2/5 2. Петя прошёл 2/5 длины дорожки , и ему осталось пройти 30 км. Какова длина дорожки? 3.Первая бригада построит дом за 54 дня , а вторая бригада за 27 дней. За сколько дней две бригады построят дом при совместной работе? 4.Делиться ли 38*756+38*239-38*281 на 19 Решите пожалуйста с решением

Answer 1

№1
(30:27-1/3)*2 1/7+2/5
30:27-1/3=30/27-9/27=21/27=7/9
№2
30:2/5=75 км- дорожка
№3
1/54x+1/27x=1
3/54x=1
x=1:3/54
x=18
Извини №4 не знаю

Answer 2

1. (30:27-1/3)*2 1/7+2/5=2 1/7+2/5=2 целых 19/35
2. 3/5- 30 км
30:3=10 (1/5)
10*5=50 км
3. 1:54=1/54 1 бригада
1:27=1/27 2 бригада
1/54+1/27=3/54=1/18 за день 1 и 2 бригада
1:1/18=18 (д) 1 и 2 бригада
Ответ: 18 дней
4. 38(756+239-281)=38*800=30400:19=1600

Answer 3

1. To evaluate the expression (30:27-1/3)*2+1/7+2/5, we can follow the order of operations (PEMDAS/BODMAS).

First, let's simplify the division: 30 divided by 27 is approximately 1.1111.

Next, let's calculate the subtraction: 1.1111 minus 1/3 is approximately 0.7778.

Now, let's multiply the result by 2: 0.7778 times 2 is approximately 1.5556.

Moving on, let's add 1/7: 1.5556 plus 1/7 is approximately 1.6122.

Finally, let's add 2/5: 1.6122 plus 2/5 is approximately 1.8122.

Therefore, the value of the expression (30:27-1/3)*2+1/7+2/5 is approximately 1.8122.

2. Let's solve the problem about Petya and the track length.

If Petya has already walked 2/5 of the track and has 30 km left to walk, we can set up the equation:

2/5 * x = 30

To find the length of the track (x), we need to solve for x.

Multiplying both sides of the equation by 5/2, we get:

x = 30 * 5/2

Simplifying, we find:

x = 75

Therefore, the length of the track is 75 km.

3. Let's solve the problem about the two brigades building a house together.

If the first brigade can build the house in 54 days and the second brigade can build the house in 27 days, we can find the number of houses each brigade can build in one day:

First brigade: 1/54 of a house per day Second brigade: 1/27 of a house per day

To find the number of houses both brigades can build together in one day, we add their rates:

1/54 + 1/27 = 3/54 + 2/54 = 5/54

Therefore, both brigades together can build 5/54 of a house per day.

To find the number of days it will take for them to build one house together, we can set up the equation:

(5/54) * x = 1

To solve for x, we multiply both sides of the equation by 54/5:

x = 54/5

Simplifying, we find:

x = 10.8

Therefore, it will take approximately 10.8 days for the two brigades to build the house together.

4. Let's solve the division problem: (38*756 + 38*239 - 38*281) divided by 19.

First, let's calculate the products:

38 * 756 = 28728 38 * 239 = 9082 38 * 281 = 10678

Next, let's calculate the sum:

28728 + 9082 - 10678 = 29032

Finally, let's divide the sum by 19:

29032 divided by 19 = 1528

Therefore, the result of the division (38*756 + 38*239 - 38*281) divided by 19 is 1528.

Please let me know if you have any further questions!