

Because half of 8 is 4

Divide 1 by 1/2 or .5... 1 becomes 1/1 and 1/2 is flipped to 2/1, then multiply
Multiplication all you have to.do is multiply the denominators.
The point (1,5) is:
Like it is shown this means that we have to move one unit in the right direction and 5 units up.
When x = 0 y = a(b)^x = a which is the y intercept
so as the y-intercept = 3 a must be = 3.