How do I solve a system of equation? Can someone explain it to me?

For example:

x - y = 4

2x + y = 5

The perimeter of a church window is 60 inches. If the window is in the shape of a regular pentagon what is the length of each side of the window

Find the surface area of the prism (8 1/4yd 12yd and 6 2/3yds)

X/8=8/18 what does x eaqual

Solve the triangle. A = 48Á, a = 32, b = 27

Big time movers charges an initial fee of $24.50, plus $12.75 an hour for their moving services On holidays they charge 2.5 times their regular total amount. If they made $188.75 on a job on Nee Year's Day, How many hours did they work

To estimate the number of people in Springfield, population 10,000, who have a swimming pool in their backyard, 250 people were interviewed. Of those, 115 had a swimming pool.

Lee put $10,000 into a stock market index mutual fund that grew at an average of 7% per year for 10 years. About how much is in Lee's mutual fund account after 10 years? Ignore compounding.

How many, and what type of, solutions does 6x^2 - 2X + 7 = 0 have? 1 rational solution 2 no real solutions 2 rational solutions 2 irrational solutions

Alice worked for six hours and earned $29.88. How much did she make per hour? A) $4.30 B) $4.98 C) $5.15 D) $179.28

Which expression is equivalent to 4/5 X 1/3? 1. 4/3 X 5/1 2. 4/5 divided by 1/3 3. 4/5 divided by 3/1