Which pair of numbers has a sum of 100?
A 57, 53
B 37, 53
C 47, 73
D 37, 63

D

Step-by-step explanation:

Add 30 and 60 and get 90 then add the leftover 7 and 3 which equals 10 now add both 90 and 10 which equals 100

- "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."