What is the first step to solving the following system of equations using substitution? x-y=7 2x-y=17 please help
Solve the first equation for x.

Multiply the first equation by 2.

Add the two equations together.

Divide the second equation by 2.

Acircle has the equation (x-2)^2 +y^2 =5. what are the coordinates of the circle's center?

Sanya noticed that the temperature was falling at a steady rate of 1.4 degrees every hour from the time that she first checked her outdoor thermometer. by 6 a.m., the temperature had fallen 21 degrees. which expression can you use to find how many hours earlier she had first checked the thermometer?

Sammie has 3 times as many goldfish as nora. nora has 4 goldfish. how many goldfish do sammie and nora have in all?