Answer:
$1.80
Step-by-step explanation:
Let the cost of a hot dog = x
The cost of a hot dog roll = y
Eight hot dogs and seven hot dog rolls cost $\$13.60$.
8x + 7x = $13.60..... Equation 1
Seven hot dogs and eight hot dog rolls cost $\$13.40$.
7x + 8x = $13.40...... Equation 2
Combining both Equation
8x + 7x = $13.60..... Equation 1
7x + 8x = $13.40...... Equation 2
Eliminating x
Multiply 1 by 7
Multiply 2 by 8
56x + 49y = 95.2..... Equation 3
56x + 64y = 107.2 ..... Equation 4
Subtracting 4 from 3
-15y = -12
y = -12/-15
y = 0.8
Cost of one hot dog roll = $0.8
Solving for x
8x + 7x = $13.60
8x + 7(0.8) = 13.60
8x + 5.6 = 13.60
8x = 13.60 - 5.60
8x = 8.0
x = 8.0/8
x = 1.
Cost of one hot dog = $1.0
The cost in dollars of a hot dog and a hot dog roll cost combined is
x + y
= $1 + $0.8
= $1.80
The answer to 9 + 4f - 7z when f = 6 and z = 5 is 9 + 4(6) - 7(5) = -2
