Tiana was going to sell all of her comic book collection to buy a video game. After selling half of them she changed her mind. She then bought nine more. How many did she start with if she now has 39?

60

Step-by-step explanation:

60 divided by 2 equals 30 + 9

step-by-step explanation:

the shape,the size and the distance

- "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."