Answer:
declaration = - 0.55 m/s²
Step-by-step explanation:
The declaration is a negative accelaration.
Therefore:

a = ?
v = 70 of 15% = 10.5 km/h to m/s = 2.9 m/s
u = 70 km/h to m/s = 19.4 m/s
t = 30 seconds

a = - 0.55 m/s²
angle 5 = angle 1 = Corresponding Angles Postulate
angle 6 + angle 5 = 180 = linear pair postulate
Answer:
x= 20
Step-by-step explanation:
The three angles add to 90 degrees
x+2x+x+10 = 90
Combine like terms
4x+10 = 90
Subtract 10 from each side
4x +10-10 = 90-10
4x = 80
Divide by 4
4x/4 = 80/4
x = 20