When Sanchez left his house this morning, his cell phone was 30% charged and it then started to lose 3% charge for each hour thereafter. Write an equation for the function B(t), representing the charge remaining in Sanchez's battery, as a percentage, t hours after he left his house.

The equation that represents the battery charge in Sanchez's phone as a percentage t hours after he left his house is B(t) = 30 - 3*t.

Step-by-step explanation:

The initial state of the battery on Sanchez's phone is 30% so in time t equals zero the battery should be at that value and as time progresses the battery should lose battery charge at a rate of 3% for each hour. We can write this in an equation form by taking the initial state and subtract it by the rate multiplied by the value of time. We have:

B(t) = 30 - 3*t

The equation that represents the battery charge in Sanchez's phone as a percentage t hours after he left his house is B(t) = 30 - 3*t.

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional