Question

1. 3\10-2\15 2,4*(-1 1/3) 2. а) -3,6х+0,8=-6,4 б) 6*(3х-0,7)=4,8 3. один кг масла м рублей а один кг творога п рублей. составьте выражение для нахождения стоимости 3 кг масла и 2 кг творога вместе. Найдите значение этого выражения, если м=160 рублей, а п=80 рублей 4. туристы были в пути три дня. в первый день они перодолели 30% всего пути, во второй 50% всего пути, а в третий - последние 49 км.Найдите длину всего пути ПОМОГИТЕ!!!!!!!!!!!!СРОЧНО!!!!!!!, зарение спасибо, ( если можно то полное решение, и способом 6 класса

Answer 1

1). Приведем к общему знаменателю. Получаем:

9/30-4/30=5/30=1/6.

24/10*-11/3=-88/10=-8,8.

2)-3,6x=-7,2

x=2

3x-0,7=0,8

3x=1,5

x=0,5

3)3m+2p

3*160+2*80=480+160=640

4)Весь путь-х. Первый день=0,3х, второй=0,5х, следовательно, третий=0,2х.

0,2х=49

х=245

Answer 2

1. Let's solve the expressions step by step:

a) 3/10 - 2/15

To subtract fractions, we need to find a common denominator, which is 30 in this case.

3/10 = 9/30 (Multiplying both numerator and denominator by 3) 2/15 = 4/30 (Multiplying both numerator and denominator by 2)

Now, we can subtract the fractions:

9/30 - 4/30 = (9 - 4) / 30 = 5/30

The result is 5/30, which can be simplified to 1/6.

b) 2.4 * (-1 1/3)

To multiply a decimal number by a mixed number, we first need to convert the mixed number to an improper fraction.

-1 1/3 = -(4/3)

Now, multiply:

2.4 * -(4/3) = -9.6/3 = -3.2

So, the result is -3.2.

2. Now let's solve the equations:

a) -3.6x + 0.8 = -6.4

To solve for x, we need to isolate it on one side of the equation. First, let's get rid of the constant term (0.8) by subtracting it from both sides:

-3.6x + 0.8 - 0.8 = -6.4 - 0.8 -3.6x = -7.2

Next, divide both sides by -3.6 to solve for x:

x = -7.2 / -3.6 x = 2

b) 6 * (3x - 0.7) = 4.8

First, distribute the 6 on the left side:

18x - 4.2 = 4.8

Now, isolate the term with x by adding 4.2 to both sides:

18x - 4.2 + 4.2 = 4.8 + 4.2 18x = 9

Finally, divide both sides by 18 to find the value of x:

x = 9 / 18 x = 0.5

3. Let's find the expression for the total cost of 3 kg of oil and 2 kg of cottage cheese:

Let m be the cost of 1 kg of oil (m = 160 rubles) Let p be the cost of 1 kg of cottage cheese (p = 80 rubles)

The total cost of 3 kg of oil is 3 * m = 3 * 160 = 480 rubles. The total cost of 2 kg of cottage cheese is 2 * p = 2 * 80 = 160 rubles.

Now, the expression for the total cost of 3 kg of oil and 2 kg of cottage cheese is:

Total cost = 480 + 160 = 640 rubles.

4. Let's find the total length of the journey:

Let the total length of the journey be x km.

In the first day, the tourists covered 30% of the total distance. That means they covered 30/100 * x = 3x/10 km.

In the second day, they covered 50% of the total distance. That means they covered 50/100 * x = x/2 km.

In the third day, they covered the last 49 km.

Now, the total distance covered in the three days is the sum of the distances covered each day:

3x/10 + x/2 + 49 = x

To solve for x, let's get rid of the fractions. Multiply the entire equation by 10 to eliminate the fractions:

10 * (3x/10) + 10 * (x/2) + 10 * 49 = 10 * x

3x + 5x + 490 = 10x

Combine like terms:

8x + 490 = 10x

Subtract 8x from both sides:

490 = 2x

Finally, divide both sides by 2:

x = 490 / 2 x = 245 km

So, the total length of the journey is 245 km.