The video tutorial covers lesson 18, focusing on writing and evaluating expressions using addition and subtraction. It includes examples involving books read by Abby and Kristin, teaching years of Darryl and Julie, and goals scored by Ian and Julia. The tutorial emphasizes using the opposite variable to solve expressions and concludes with an exercise on visits to Niagara Falls.

What is the first step in writing an expression for a story problem?

• Identify the known quantities

• Identify the unknown quantity

• Draw a picture

• Solve the expression

If Abby read 8 more books than Kristin, and Kristin read 9 books, how many books did Abby read?

• 19

• 18

• 15

• 17

In the second marking period, if Abby read 6 more books than Kristin and Abby read 20 books, how many books did Kristin read?

• 16

• 12

• 18

• 14

What is the key concept to remember when choosing a variable for an unknown quantity?

• Use any variable you like

• Use the opposite variable of what you are looking for

• Use a different variable for each problem

• Use the same variable as the known quantity

What is the expression for the number of books Kristin read if Abby read 6 more books than Kristin?

• A + 6

• K + 6

• A - 6

• K - 6

Darryl has been teaching for one year longer than Julie. If Julie has been teaching for 28 years, how long has Darryl been teaching?

• 30 years

• 29 years

• 28 years

• 31 years

How do you determine the expression for the number of years Darryl has been teaching compared to Julie?

• Multiply Julie's years by two

• Add one to Julie's years

• Subtract one from Julie's years

• Divide Julie's years by two

Ian scored 4 fewer goals than Julia. If Julia scored 13 goals, how many goals did Ian score?

• 10

• 7

• 9

• 8

If Ian scored 3 fewer goals than Julia in the second half, and Ian scored 8 goals, how many goals did Julia score?

• 12

• 13

• 11

• 10

What is the expression for the number of goals Ian scored if he scored 4 fewer than Julia?

• I - 4

• J - 4

• I + 4

• J + 4