75. Sailing A sailboat begins a voyage with 145 lb of food. The crew plans to eat a total of 15 lb of food per day.

    1. Write an equation in slope-intercept form relating the remaining food supply y to the number of days x.
    2. Graph your equation.
    3. The crew plans to have 25 lb of food remaining when they end their voyage. How many days does the crew expect their voyage to last?

Standardized Test Prep

SAT/ACT

76. Which equation represents the line that has slope 5 and passes through the point ( 0 , − 2 ) ? open 0 comma negative 2 close question mark

    1. y = x − 2 y equals x minus 2
    2. y = 5 x − 2 y equals 5 x minus 2
    3. y = − 2 x − 5 y equals negative 2 x minus 5
    4. y = 5 x y equals 5 x

77. What is the slope of the line that passes through the points ( − 5 , 3 ) open negative 5 comma 3 close  and (1, 7)?

    6. − 5 3 negative , 5 thirds
    7. − 2 3 negative , 2 thirds
    8. 2 3 2 thirds
    9. 3 2 3 halves

78. Which number line shows the solution of | 2 x + 5 | ≤ 3 ? vertical line 2 x plus 5 vertical line less than or equal to 3 question mark

    1. 
    2. 
    3. 
    4. 

79. Which equation represents the graph below?

    6. y = − 3 2 x + 4 y equals negative , 3 halves , x plus 4
    7. y = − 4 x + 3 2 y equals negative 4 x plus , 3 halves
    8. y = − 2 3 x + 4 y equals negative , 2 thirds , x plus 4
    9. y = 4 x − 2 3 y equals 4 x minus , 2 thirds

Short Response

80. If a, b, and c are real numbers, a ≠ 0 , eh not equal to 0 comma  and b > c , b greater than c comma  is the statement a b > ac eh b greater than ac  always, sometimes, or never true? Explain.

Mixed Review

See Lesson 5-2.

Suppose y varies directly with x. Write a direct variation equation that relates x and y. Then find the value of y when x = 10 . x equals 10 .

81. y = 5  when  x = 1 . y equals 5 , when , x equals 1 .
82. y = 8  when  x = 4 . y equals 8 , when , x equals 4 .
83. y = 9  when  x = 3 . y equals 9 , when , x equals 3 .

See Lesson 2-2.

Solve each equation. Justify each step.

84. 21 = − 2 t + 3 21 equals negative 2 t plus 3
85. q 3 − 3 = 6 q over 3 , minus 3 equals 6
86. 8 x + 5 = 61 8 x plus 5 equals 61

Get Ready! To prepare for Lesson 5-4, do Exercises 87–90.

See Lesson 1-7.

Simplify each expression.

87. − 3 ( x − 5 ) negative 3 open x minus 5 close
88. 5 ( x + 2 ) 5 open x plus 2 close
89. − 4 9 ( x − 6 ) negative , 4 ninths , open x minus 6 close
90. 1.5 ( x + 12 ) 1.5 open x plus 12 close

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