7.2 Solving Systems of Equations by Substitution

Day Two

Solving Systems of Equations by Substitution

Step 2

Step 3

Step 4

Step 5

Step 1 Solve for one variable in one equation.

Substitute the resulting expression into the other equation.

Now solve that equation to get the value of the first variable.

Substitute that value into either one of the original equations and solve for the other variable.

Write the values from steps 3 and 4 as an ordered pair, (x, y), and check.

Steps for Solving by Substitution

Worksheet Answers #1-6

1. (-1,-4)

2. No solution

3. (5, 3)

4. Infinite Solutions

5. (4, -2)

6. (3, 5)

7.) One hot air balloon is 10 meters above the ground and rising 15 meters per minute. A second balloon is 150 meters above the ground and descending 20 meters per minute. In how many minutes will they be at the same height? What height will they be at that time?

8.) Movie tickets at a local theater cost $6 for adults and $2 for children under twelve. If 175 tickets were sold, with cash receipts of $750, how many children tickets were sold?

9.) A chemistry lab can be used by 38 students at one time. The lab has 16 workstations, some set up for two students each and the others set up for three students each. How many workstations accommodate two students?

10.) A forty foot rope is cut into two pieces. The length of one piece is 9 times the length of the other. What is the length of the longer piece?

11.) Michael and Monica Gordon both want to buy a new X-Box. Monica has already saved $25 and plans to save $5 per week. Michael has $16 and plans to save $8 per week. After how many weeks will they have the same amount saved? How much will each have saved at this time?