Use the substitution to solve the system of equations

y = - 2x

x-3y=21

Find the perimeter of a triangle with sides measuring 3 centimeters, 4 centimeters and 5 centimeters. a. 20 cm c. 19 cm b. 12 cm d. 14 cm

Mark has a certain number of songs on his MP3 player. Each week, he plans to add 4 more songs. After 5 weeks, he had 40 songs on his MP3 player. Which statement is true? A. Mark adds 5 songs on his MP3 player per week. B.

If the volume of a sphere is 288 (3.14) what is the surface area

A cylinder with a radius of 4 cm and a height of 6 cm is inside of a sphere with a radius of 10 cm. How much space is inside the sphere, but outside a cylinder? Round to the nearest tenth if necessary. Use 3.14 for pi.

Suppose $1,000 is compounded quarterly for 4 years. what rate is needed to reach a total of $1,500? round to the nearest tenth of a percent.

I am testing the value of the hole number 857

What is the difference 4 1/3 - (-2/3)

Twice the sum of x is at most 38. what is the greatest value of x that satisfies the inequality that represents this situation

The moon has a radius of 1736 1736 kilometers. The earth has a radius of 6371 6371 kilometers. How many times as large is the volume of the Earth as the volume of the moon, rounded to the nearest whole number?

You want to go to europe 5 years from now, and you can save $3,800 per year, beginning one year from today. you plan to deposit the funds in a mutual fund that you think will return 8.5% per year.