Roslan had a total of $50 in 10-cent coins,20-cent coins and 50-cent coins. The value of his 10-cent coins was 30% of the total value of all his coins. The value of his 20-cent coins was 28% of the total value of all his coins. What was the value of his 50-cent coins?

$21

Step-by-step explanation:

Provided total value = $50

$50 = 5,000 cents.

We are provided,

10 cent coins value = 30%  of total value

= 0.3 5,000 cents = 1,500 cents

Value of 20 cents coin = 28% of total value

= 0.28 5,000 cents = 1,400 cents

Therefore, remaining value of cents = Total value of 50 cents coins

5,000 cents - value of 10-cent coins - value of 20-cent coins = total value of 50 cents coins

5,000 - 1,500 - 1,400 = 2,100 cents = $21

Which means number of 50 cents coin =

Alternatively,

To calculate value of 50 cent coins

Total value = 100%

Value in 10-cent coins + 20-cent coins = 30% + 28% = 58%

Value in 50-cent coins = 100 - 58 = 42%

= $50 42% = $21

0.6

39mph

step-by-step explanation:

- "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."