Can anyone explain to me how to solve systems of equations with three variables? especially for this problem

x-3z=7

2x+y-2z=11

-x-2y+2z=6

Which addition property is demonstrated by this problem? 23 + (4 + 3) = (23 + 4) + 3

The circle has an angle of 40° and an area of 8 cm2. Calculate the area of the entire circle.

4. Data are collected on the amount of fat (in grams) and calories in the french fry orders at nine fast food restaurants. The least-squares regression line for the data is û = 274.34 + 9.

a local pizzeria sold 72 pizza's yesterday. The owner offers the emplyees a bonus if the number of pizza's sold increases by 30% today. How many total pizza's must the pizzeria sell for emplyees to recieve the bonus?

Each month, Jackie budgets $1640 for fixed expenses, $1320 for living expenses, and $260 for annual expenses. Her annual net income is $38,640. Which statement best describes her monthly budget? It shows a deficit of $260. It shows a surplus of $260.

How do you multiply a mixed fraction by a regular fraction

Roger has 4 gallons of juice. He puts the same amount of juice into each of 5 pitchers. How many gallons of juice are in 1 pitcher?

400 students were randomly sampled from a large university, and 289 said they did not get enough sleep. Conduct a hypothesis test to check whether this represents a statistically significant difference from 50%, and use a significance level of 0.01.

Round off the number of seconds in an hour to 1 significant figure number of seconds = 3600

The sum of two numbers is 50. Two times the smaller number exceeds the larger number by 31. Find the numbers.