Liza comes to the swimming pool once every 6 days. Jenny comes once every 4 days and Olga comes once every 10 days. This Monday all of them were in the pool.
How many days after this Monday will all of them meet at the swimming pool again?

60 days

Step-by-step explanation:

L.C.M. of 6,4,10=60

as 6=2×3

4=2×2

10=2×5

L.C.M. =2×3×2×5=60

after 60 days they will again together.

i think c. but don't trust it.

step-by-step explanation:

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional