If by decomposition you mean breaking it ino parts then
break it itno 2 triangles and 1 rectangle
left to right
triangle with base y and height h
h=10
y=3
area of traignel=1/2bh
aera=1/2(10)(3)
area=5(3)
area=15
rectangel of legnth x and height h
area=legnth timwe width
x=8
h=10
area=8 times 10
aera=80
last triangle
should be same as other sinces same base (y) and same height (h)
15
add
15+80+15=120
Y=3x has a positive slope, and Y=-3x has a negative slope.
The answer to that question is (5x+3).
Answer:

Step-by-step explanation:
We are given a graph and asked to find the slope.
So we can see two coordinate points, one on (0, 3) and (2, 0).
When trying to find slope, we use the method rise over run, which basically means y over x as a fraction, in which you then divide.
So count how many times it'll take for x to get to y, base it off the picture below
Since we see our numbers to be divided are 3 over 2, do the division and you get 1 1/2.
Would this be negative though? No, since the graph is in an increase, not a decrease.