Kyle and josh have a total of 64 CDs. Kyle has 12 more CDs than josh. How many CDs does each boy have?

Work Shown:

K = number of CDs Kyle has

J = number of CDs Josh has

K+J = 64 because they have 64 CDs combined

K = J+12 since Kyle has 12 more CDs than Josh does.

We will use substitution to eliminate one variable

K+J = 64

J+12+J = 64 ... replace K with J+12. This is valid because K = J+12

2J+12 = 64

2J+12-12 = 64-12 ... subtract 12 from both sides

2J = 52

2J/2 = 52/2 divide both sides by 2

J = 26

Josh has 26 CDs

Use this to find the value of K

K = J+12

K = 26+12

K = 38

Kyle has 38 CDs

As a check, add up the amounts Kyle and Josh has to get

K+J = 38+26 = 64

So this confirms the answer.

- "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."