20 = 2 x 2 x 5
15 = 3 x 5
common divisor (CD) of 20 and 15 is 5 so n should be 5 and each group has 4 boys and 3 girls.
If there are more than one CD, then there are more than one answer.
If they ask for the largest number of groups, greatest common divisor (GCD) will be the answer.
Answer:
one solution
Step-by-step explanation:
Alright,
you will need to solve for each variable to find if they got the equation correctly or not..
Let's start with h
isolate h
(1/2)h = A/(b1+b2)
Now we need to get rid of 1/2 we may do so by multiplying both sides by 2
h = 2(A/(b1+b2))
And that's not how they did it for h so Option D doesn't apply
Let's see C
Also doesn't apply since they multiplied 2 only by A rather than A/h
Let's see B
Also not correct they made the same mistake as with option C
Let's see A
again same mistake
when multiplying both sides by 2
the 2 should be as following

I believe you should contact your instructor and explain that non of the options is right.