If a number is a natural number it is a complex number

The answer to this is yes. Natural numbers are a subset of the integers which are a subset of the reals which are complex numbers. A complex number can also be written as a+bi, which a real number has imaginary part 0, so just a. An integer is a number that can be written without a fractional or decimal component, and a natural number is an integer that is at least 0. Either way, a natural number is a complex number.

answer: i think it is (1,-2)

- "runner b is moving at a slower rate."

- "the graphs shown are graphs of distance(km) against time(min).

the slopes of this graphs are are given by:

slope = (change in y)/(change in x)

= (change in distance)/(change in time)

this is the formula for finding the speed. so, the slope of these graphs represent the speed of the runner.

taking each division in the graph to represent 1 on both axis:

runner a ⇒ speed = (2-0)/(1-0)

= 2/1

= 2 km/min

runner b ⇒ speed = (3-0)/(3-0)

= 3/3

= 1 km/min

this shows that   runner b is moving at a slower rate."