Answer:

Step-by-step explanation:
Perimeter of the rhombus, STAR, is the sum of the length of all it's 4 sides.
The coordinates of its vertices are given as,
S(-1, 2)
T(2, 3)
A(3, 0)
R(0, -1)
Length of each side can be calculated using the distance formula given as 
Find the length of each side ST, TA, AR, RS, using the above formula by plugging in the coordinate values (x, y) of each vertices.

S(-1, 2) => (x1, y1)
T(2, 3) => (x2, y2)



T(2, 3) => (x1, y1)
A(3, 0) => (x2, y2)



A(3, 0) => (x1, y1)
R(0, -1) => (x2, y2)



R(0, -1) => (x1, y1)
S(-1, 2) => (x2, y2)




When you multiply powers with the same base, you sum the exponents:

So, in this case, you have

To find the center of enlargement, draw a line that connects corresponding vertices, as shown below.
The transformation that map RST to R'S'T' is an enlargement with scale factor of 3 and center of (0,0)
Answer:
- Melissa: 30
- Ryan: 23
- Chau: 69
Step-by-step explanation:
Let r represent the number of messages Ryan sent. Then Chau sent 3r and Melissa sent r+7. Their total was ...
(r+7) +(r) +(3r) = 122
5r +7 = 122 . . . . . collect terms
5r = 115 . . . . . . . . subtract 7
r = 23 . . . . . . . . . . divide by 5
Ryan sent 23, Melissa sent 30, and Chau sent 69 text messages.