12a)
5x + 45 + 3x - 25 = 180
8x + 20 = 180
8x = 160
x = 20
12b)
2x - 5 = 2(20) - 5 = 40 - 5 = 35
3x - 25 = 3(20) - 25 = 60 - 25 = 35
y = 180 - (35+35)
y = 180 - 70
y = 110
Answer:
the graph corresponds to function "D" 
Step-by-step explanation:
Since the graph shown corresponds to an exponential "decay" (the function decreases as we move from left to right), the base of the exponent has to be a number smaller than 1 (one). So we examine the only two options that give such (options C and D which have fractions as the base - 1/3 and 1/5 respectively)
From there, we analyze which of the two functions satisfies the crossing of the y-axis at (0,3) which is clearly shown in the graph:
We study both:
function C at x = 0 gives:

while function D at x = 0 gives:

Therefore, the graph corresponds to function "D"
I am giving the answers only.
2/5
4/7
5/11
1/5
2/3
3/5
2/15
1/2
Answer:
h= 12.98 metres
Explanation:
The tree is leaning over so, the triangle is no longer right-angled.