1. t+b=280
2t+3b=660
b=-t+280
2t-3t+840=660
-t=-180
t=180
b=100
He sold 180 tacos and 100 burritos
2. x=5 cent pencils
y=10 cent pens
x+y=1000
.05x+.1y=74.5
y=-x+1000
.05x-.1x+100=74.5
-1.5x=-25.5
15x=255
x=17
y=983
They sold 17 pencils and 983 pens
0=7x+14-4
0=7x+12
7x=-12
x=-12/7
A is equal to 907 but not 907.3
So D is the answer
Answer:
Step-by-step explanation:
The initial temperature difference of 72 -34 = 38 °F is reduced to a difference of 72 -41 = 31 °F after 35 minutes. The exponential term in the temperature expression could have the factor ...
(31/38)^(t/35) = e^(-kt)
Taking the natural log, we find ...
(t/35)ln(31/38) = -kt
k = ln(38/31)/35 ≈ 0.00581711
To the nearest thousandth, this is ...
k ≈ 0.006
Using this in the equation for temperature, we have ...
T = 72 -38e^(-0.006t)
Filling in the desired value for t (80), we find the turkey temperature after 80 minutes to be about
T = 72 -38e^(-.006×80) = 72 -38e^-.48 ≈ 48.49
T ≈ 48 °F
The value of k is about 0.006, and the turkey temperature is about 48 °F.
Answer:192$
Step-by-step explanation: