The larger number is 30.
Set up your equation.
x + y = 25
The question tells us one number is 5 less than the other.
The equation now becomes
x -5 = 25
Add 5 to each side to isolate x.
x=30
Multiply 2/10 by 3/1 and you should end up with 6/10
Since we already know that the older child is a girl (a 100% chance to be a girl), there must be a 50% chance that the other child is a girl. Therefore, the probability that both children are girls is 50%.
Hope this helps!
1/4 times 2 2/3 = 2/3
Change from a mixed number to improper fraction: 1/4 times 8/3
Multiply across so 1x8/4x3 to get 8/12
Simplify to 2/3
The correct solution is 75.
