7. Systems of Equations & Matrices

In Exercises 5–18, solve each system by the substitution method.x + y = 4y = 3x

A chemist needs to mix a solution that is 34% silver nitrate with one that is 4% silver nitrate to obtain 100 milliliters of a mixture that is 7% silver nitrate. How many milliliters of each of the solutions must be used?

In Exercises 5–18, solve each system by the substitution method.x + 3y = 8y = 2x - 9

Solve each system by substitution. See Example 1. 4x + 3y = -13-x + y = 5

Solve each system by substitution. See Example 1.x - 5y = 8 x = 6y

The perimeter of a table tennis top is 28 feet. The difference between 4 times the length and 3 times the width is 21 feet. Find the dimensions.

In Exercises 5–18, solve each system by the substitution method.x = 4y - 2x = 6y + 8

Solve each problem. Alcohol MixtureBarak wishes to strengthen a mixture that is 10% alcohol to onethat is 30% alcohol. How much pure alcohol should he add to 12 L of the 10% mixture?

In Exercises 5–18, solve each system by the substitution method.5x + 2y = 0x - 3y = 0

In Exercises 5–18, solve each system by the substitution method.2x + 5y = - 43x - y = 11

Solve each system by substitution. See Example 1.7x - y = -10 3y - x = 10

In Exercises 5–18, solve each system by the substitution method.2x - 3y = 8 - 2x3x + 4y = x + 3y + 14

Solve each system by substitution. See Example 1.-2x = 6y + 18 -29 = 5y - 3x

Solve each problem using a system of equations. A company sells recordable CDs for $0.80 each and play-only CDs for $0.60 each. The company receives $76.00 for an order of 100 CDs. However, the customer neglected to specify how many of each type to send. Determine the number of each type of CD that should be sent.

In Exercises 5–18, solve each system by the substitution method.y = (1/3)x + 2/3y = (5/7)x - 2