Which calculations could be used to solve this problem?

there are 21 children at corie's party. there are 2 times as many girls as boys at the party.

how many girls are at the party?

choose all answers that are correct.

a.
multiply 21 × 2. divide the product by 3.

b.
add 21 + 2. divide the sum by 3.

c.
divide 21 ÷ 3. subtract the quotient from 21.

d.
divide 21 ÷ 3. multiply the quotient by 2.

(23*2)-12=x     x=34

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."