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

For example:

x - y = 4

2x + y = 5

Mother is m years old, and she is four times as old as her daughter. How much older is the mother than her daughter?

Select the proper placement for parentheses to speed up the addition for the expression 2 + 9 + 8 + 1 A. (1 + 2) + (9 + 8) B. (9 + 2) + (8 + 1) C. (8 + 2) + (9 + 1) D. (8 + 9) + (2 + 1)

What causes the Earth to have magnetic field?

What is the tan of 30 degrees

Given ƒ (x) = - 10x + 45, find x when ƒ (x) = 15.

The local bike shop sells a bike and accessories package for $225. If the bike is worth 8 times more than the accessories, how much does the bike cost?

Matti has 1 more pencils than Chang lin. Renaldo has three times as many as Chang lin.

Rearrange the following group of numbers from smallest to largest. 2.7, 2.06, 2

Is it possible for the area of a figure to change after it is translated?

The larger of two number is 12 more than smaller number. If the sum of the two numbers is 74, find the two numbers