Page 100 - Math Course 1 (Book 1)

Expressions Containing Variables

z-x
MO. 3 - L2b Evaluate if x = 3, y = 4, and z = 7.
y
Evaluate Expressions z-x = (z - x) y write as a division
÷
y
Containing Variables expression.
÷
= (7 - 3) 4 Replace z with 7, x with
3, and y with 4.
Vocabulary A-Z = 4 4 Subtract.
÷
Let us learn some vocabulary
= 1 Divide

Answer 1
Variable

is a placeholder for any value. It is unknown. Any Evaluate 5z + (x + 4y) –15 if x = 3, y = 4, and
letter can be used as a variable. z = 7

3 + y y is the variable 5z + (x + 4y) – 15 = 5(7) + (3 + 4 4) – 15

4d d is the variable Replace z with 7, x with 3, and y with 4.
= 5(7) + (3 + 16) – 15 Multiply 4 and 4.

= 5(7) + 19 – 15 Add 3 and 16.
Let’s Begin
= 35 + 19 – 15 Multiply 5 and 7

= 54 – 15 Add 35 and 19.
Evaluate Expressions
= 39 Subtract 15 from 54.

Examples Answer 39

Evaluate x – y + 6 if x = 27 and y = 12.
REAL WORLD EXAMPLE
x – y + 6 = 27 – 12 + 6 Replace x with 27 and y
with 12.
THEATER
= 15 + 6 Subtract 12 from 27. East Middle School sold tickets for
a school play. The price of an adult
= 21 Add 15 and 6. ticket was $3 and the price of a student ticket
was $1. Suppose 70 adult tickets and 85
student tickets were sold.
Answer 21
How much money was collected?
. Evaluate 6y – 4x if x = 3, y = 4, and z = 7.
3a + 1s = 3(70) + 1 (85) Replace a with 70 and
s with 85.
6y – 4x = 6(4) – 4(3) Replace y with 4 and x
with 3.
= 210 + 85 Multiply.
= 24 – 12 Multiply.
= 295 Add.
= 12 Subtract.

Answer 12 Answer The amount of money
collected was $295.

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