Answer : The cost of 10 balls will be, 13.5 dollars
Step-by-step explanation :
As we are given the following expression:
where,
P = total price (in dollars)
n = number of balls used
Given:
n = number of balls used = 10
Now we have to determine the cost of 10 balls.
Thus, the cost of 10 balls will be, 13.5 dollars
Answer: $19.6
Step-by-step explanation:
Linear function: f(x)=mx+c
, where m= rate of change in f(x) with respect to x.
c = Initial value.
Let c = Initial value of card , m= Charge per minute
x= Number of minutes calling time.
Then, 25.06= 38m+c (i)
21.03=69m+c (ii)
Eliminate (ii) from (i)
Put m in (i) , we get
i.e. f(x)=-0.13x+30
if x=80 then
f(80)= -0.13(80)+30
=-10.4+30
=19.6
Hence, the remaining credit after 80 minutes of calls = $19.6