Ice is placed around a bowl of water to lower the temperature. The equation D=−75t+22 shows the time, t, measured in minutes and temperature, D, measured in degrees Celsius. Which statement is correct?

d) Before cooling begins, the temperature of the water is 22°C

Step-by-step explanation:

Option A

If t=7 minutes

D=-7/5t+22

=-7/5(7)+22

=-49/5+22

=-49+110/5

=61/5

=12.2°C

Change in temperature=12.2°C-22°C

=-9.8°C

Option B

If t=5 minutes

D=-7/5t+22

=-7/5*5+22

=-7+22

=15°

Change in temperature=15°-22°

=-7°

Option C

The temperature of the ice must be less than 22°C

Option D

D=-7/5t+22

When ice is not placed, t=0

D=-7/5t+22

=-7/5(0)+22

=0+22

=22

Temperature of the water before cooling=22°

set each factor equal to 0

4x-3 = 0

2x-1 = 0

solve for x.

4x-3=0

4x=3

x= 3/4

solve for x. 

2x-1= 0

2x= 1

x= 1/2

eventually after a few more steps, your answer should be 1/2 is less than or equal to x and 3/4 is greater than or equal to x