Answer:
21
Step-by-step explanation:
If 2/7th of Eva's grandchildren live in one location, we know that 5/7th (the remaining portion of Eva's grandchildren) must live in the other location
Wales + Australia = all of the kids (100% = 1/1 (which is equal to 7/7) )
Wales + Australia = 7/7ths
{x is the total number of kids}
Australia = 5/7ths
15 =
{multiply both sides by 7 to get rid of fraction}
105 = 5x {divide both sides to find 1x}
21 = x
check:
2/7th of 21 = 6
5/7th of 21 = 15 {which we know}
6 + 15 = 21
21 = 21
(TRUE)
So, Eva has 21 grandchildren
hope this helps!!