43. Physics The force you need to apply to a lever varies directly with the weight you want to lift. Suppose you can lift a 50-lb weight by applying 20 lb of force to a certain lever.

    1. What is the ratio of force to weight for the lever?
    2. Write an equation relating force and weight. What is the force you need to lift a friend who weighs 130 lb?

C Challenge

The ordered pairs in each exercise are for the same direct variation. Find each missing value.

44. (3, 4) and (9, y)
45. (1, y) and ( 3 2 , − 9 ) open , 3 halves , comma negative 9 close
46. ( − 5 , 3 ) open negative 5 comma 3 close  and ( x , − 4.8 ) open x comma negative 4.8 close

47. Gas Mileage A car gets 32 mi per gallon. The number of gallons g of gas used varies directly with the number of miles m traveled.

    1. Suppose the price of gas is $3.85 per gallon. Write a function giving the cost c for g gallons of gas. Is this a direct variation? Explain your reasoning.
    2. Write a direct variation equation relating the cost of gas to the miles traveled.
    3. How much will it cost to buy gas for a 240-mi trip?

Standardized Test Prep

GRIDDED RESPONSE

SAT/ACT

48. The price p you pay varies directly with the number of pencils you buy. Suppose you buy 3 pencils for $.51. How much is each pencil, in dollars?
49. A scooter can travel 72 mi per gallon of gasoline and holds 2.3 gal. The function d(x) = 72x represents the distance d(x), in miles, that the scooter can travel with x gallons of gasoline. How many miles can the scooter go with a full tank of gas?

50. The table below shows the number of hours a clerk works per week and the amount of money she earns before taxes. If she worked 34 h per week, how much money would she earn, in dollars?

    Weekly Wages

    Time (h)	Wages ($)
    12	99.00
    17	140.25
    21	173.25
    32	264.00

51. What is the greatest value in the range of y = x 2 − 3 y equals , x squared , minus 3  for the domain { − 3 , 0 , 1 } ? left brace negative 3 comma 0 comma 1 right brace question mark

Mixed Review

See Lesson 5-1.

Find the slope of the line that passes through each pair of points.

52. (2, 4), (0, 2)
53. (5, 8), ( − 5 , negative 5 comma  8)
54. (0, 0), (3, 18)
55. (1, − 2 negative 2 ), ( − 2 , negative 2 comma  3)

Get Ready! To prepare for Lesson 5-3, do Exercises 56–59.

See Lesson 1-2.

Evaluate each expression.

56. 6 a + 3  for  a = 2 6 eh plus 3 , for , eh equals 2
57. − 2 x − 5  for  x = 3 negative 2 x minus 5 , for , x equals 3
58. 1 4 x + 2  for  x = 16 1 fourth , x plus 2 , for , x equals 16
59. 8 − 5 n  for  n = 3 8 minus 5 n , for , n equals 3

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