I think boys =18
girls=12
boys :x
girls:y
student:z
the number of group for the boys :n
the numberof group for the girls :m
so x=(3/5)*z
y=(2/5)* z
x/y=3/2
3y-2x=0
(1/10)*z*n=(3/5) *z
so n=6
(1/5)*z*m=(2/5)* z
put x=(1/10)*z*6
y=(1/5)*z*2
into 3y-2x=0 and z=30
z=30 so x=(1/10)*30*6=18
y=(1/5)*30*2=12
First one is 7t because the s cancels out and -28/-4 = 7 and the other one would be 78 + 5 + 7 because adding is the opposite of subtracting.
Given:
The sequence is
436, 218, 109, 54.5, 27.25,...
To find:
The explicit formula for the given sequence.
Solution:
We have,
436, 218, 109, 54.5, 27.25,...
It is a GP because the two consecutive terms have common ratio.
Here,
First term : a=436
Common ratio : d = 
= 
= 
Now, the explicit formula for a GP is

Where, a is the first term and r is the common ratio.
Putting a=436 and r=0.5, we get

Therefore, the correct option is c.