Ans given below
-3r-12=-21
-3r=-21+12
-3r=-9
r=-9\-3
r=3
Answer:

Step-by-step explanation:

Answer:
The function notation is given as:
$6 + $30 × x
f(x) = $6 + 30x
The dog walker charges $28.50
Step-by-step explanation:
Let the hourly rate be represented by x
A dog walker charges a flat rate of $6 per walk plus an hourly rate of $30.
The function notation is given as:
$6 + $30 × x
F(x) = $6 + 30x
How much does the dog walker charge for a 45 minute walk?
We have to convert 45 minutes to 1 hour
60 minutes = 1 hour
45 minutes = x
x = 45/60
x = 3/4(hour)
Putting that in the function notation:
f(x) = $6 + 30x
x = 3/4
$6 + 30(3/4)
$6 + $22.5
= $28.50
Therefore, the dog walker charges $28.50
Answer:
The number of boys who play tennis is 36.
Step-by-step explanation:
Let the number of boys who play tennis is x.
number of boys who play cricket = y
x = 3 y..... (1)
12 boys plays both cricket and tennis.
According to the question,
x - 12 = y + 1 2
3 y - 12 = y + 12
2 y = 24
y = 12
So, the number of boys who plays tennis is x = 3 x 12 = 36.