Answer:
a) b = -5
b) slope = 3/2
Explanation:
a) The equation of a line is given as y = mx + b, where m is the slope of the line and b is the intercept on the y axis.
Given that y = 3x + b and it passes through the point (2, 1). Hence when x = 2, y = 1. Therefore, substituting for x and y:
1 = 3(2) + b
1 = 6 + b
b = 1 - 6
b = -5
b) The equation of a line passing through two points (
) and
is given by:

The equation of the line passing through the two points (0,3) and (4,9) is:

Comparing y = (3/2)x + 3 with y = mx + b, the slope (m) is 3/2
Answer:
C
Explanation:
A theory can be changed when new evidence is found. A law doesn't change because it is universally a fact. It doesn't need new evidence to support it.
The motion of the light is a uniform motion with constant speed

, therefore we can use the basic relationship between speed, space and time:

(1)
where S is the distance covered and t is the time taken. The light takes t=1.3 s to travel from the moon to Earth, therefore by rearranging eq.(1) we can find the distance between the Moon and the Earth:
This is true due to the reaction that happens from water evaporating and leaving the sugar crystals behind to form.