7th Grade Math

(Marvins-Underground-K-12) #1
36 Expressions and Patterns

Examples 1–3 Evaluate each expression if m = 2, n = 6, and p = 4.


  1. n - p 2. 7 m - 2 3. 3 m + 4 p

  2. n 2 + 5 55 _mn
    4

  3. _^5 n^ +^ m
    8
    Example 4 7. HEALTH The standard formula for finding your maximum heart rate is
    220 - a, where a represents a person’s age in years. What is your
    maximum heart rate?


Examples 5 and 6 8. MUSIC A Web site charges $0.99 to download a song and a $12.49
membership fee. Write an expression that gives the total cost in dollars
to download any number of songs. Then find the cost of downloading
6 songs.

= Step-by-Step Solutions begin on page R1.
Extra Practice begins on page EP2.

Examples 1–3 Evaluate each expression if d = 8, e = 3, f = 4, and g = 1.


  1. d + 9 10. 10 - e 11. 4 f + 1 12. 8 g - 3

  2. _d
    4

  3. _^16
    f

  4. _^5 d^ -^25
    5




(5 + g)^2
_
2


  1. 6 f 2 18. 4 e 2 19. d 2 + 7 20. e 2 - 4


Example 4 21. BOWLING The expression 5n + 2 can be used to find the total cost in
dollars of bowling where n is the number of games bowled and
2 represents the cost of shoe rental. How much will it cost Vincent to
bowl 3 games?


  1. HEALTH The expression _ 30 w , where w is a person’s weight in pounds, is
    used to find the approximate number of quarts of blood in the person’s
    body. How many quarts of blood does a 120-pound person have?


Examples 5 and 6 CARS A car rental company’s fees are shown.
2323 Suppose you rent a car using Option 2.

Car Rental Prices
Option 1 Option 2


  • $19.99 per day

  • $0.17 per mi

    • $50 fee
      i • $0.17 per mi $0.17 per mi




Write an expression that gives the
total cost in dollars for driving any
number of miles. Then find the cost
for driving 150 miles.


  1. Suppose you rent a car using Option 1.
    Write an expression that gives the
    total cost in dollars to rent a car for
    d days and m miles. Then find the cost for
    renting a car for 2 days and driving 70 miles.


Evaluate each expression if x = 3.2, y = 6.1, and z = 0.2.


  1. x + y - z 26. 14.6 - (x + y + z) 27. xz + y 2


B

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