Find the ratio of male teachers to male students At a school function, the ratio of teachers to students is $5:18$. The ratio of female students to male students is $7:2$. If the ratio of the female teachers to female students is $1:7$, find the ratio of the male teachers to male students. 
 A: Let's say that there are $T_f$ female teachers, $T_m$ male teachers, $S_f$ female students, and $S_m$ male students. You are given that,
$$
(T_f + T_m) / (S_f + S_m) = 5/18\\
S_f / S_m = 7/2\\
T_f / S_f = 1/7
$$
And what you want to find is,
$$
T_m / S_m
$$
You can solve this now by substituting in the things you already know,
$$
T_f = 1/7 \times S_f \\
S_m = 2/7 \times S_f \\
T_m = 5/18 \times (S_f + S_m) - T_f
$$
So,
$$
\begin{aligned}
T_m/S_m &= T_m / S_f \times S_f / S_m \\
&= (5/18 \times (S_f + S_m) - T_f) / S_f \times 7/2 \\
&= (5/18 \times (S_f + 2/7 \times S_f) - 1/7 \times S_f) / S_f \times 7/2 \\
&= (5/18 \times (1 + 2/7) - 1/7) \times 7/2 \\
&= 3/4
\end{aligned}
$$
A: Lets consider there are 7 female student and 2 male student.(7:2)
total student = 9
teacher : student = 5:18
therefore for 18 student there will be 14 girls and 4 boy students
5:14:4
now only 1 female teacher is required for 7 female students (1:7)
here we have 14 female students hence 2 female teacher is required
and total teacher is 5 
out of it 2 are female hence 3 teacher are male
5:14:4(teacher:female student:male student)
3:2:14:4(male teacher: female teacher :female student:male student)
hence 3: 4
this is what i found if its wrong please reply
A: Let A = # of Female Teachers
Let B = # of Male Teachers
Let X = # of Female Students
Let Y = # of Male Students
Then the statement "the ratio of Teachers to students is 5:18" can be represented by the following equation, EQ1:
EQ1: (A+B)/(X+Y) = 5/18 _________(A+B = number of teachers, X+Y = number of students)
 18*(A+B) = 5*(X+Y) _________(Still EQ1)

 18*A + 18*B = 5*X + 5*Y ____(Still EQ1)

The statement "the ratio of famale students to male students can be represented by the following equation, EQ2: 
EQ2:  X/Y = 7/2  -->  X = (7/2)*Y
The statement "the ratio of female teachers to female students can be represented by the following equation, EQ3: 
EQ3: A/X = 1/7  -->  A = X/7
We want to solve for the ratio of male teachers (B) to male students (Y)
In order to do that, we want first want to substitute X in EQ3 with the value of X defined in EQ2
A = X/7 
A = (7/2)*Y/7 ____________(substituted (7/2)*Y for X)
A = Y/2  ________________ (We will call this EQ4)
Now, we want to substitute X in EQ1 with the value of X defined in EQ2, and A in EQ1 with the value of A defined in EQ4, and solve for B/Y.
18*A + 18*B = 5*X + 5*Y _____________________(EQ1 from above)
18*(Y/2) + 18*B = 5*((7/2)*Y) + 5*Y _________(Substituted for A and X)
9*Y + 18*B = 17.5*Y + 5*Y
18*B = 17.5*Y + 5*Y - 9*Y
18*B = 13.5*Y
B/Y = 13.5/18 = 3/4
Therefore, the ratio of male teachers to male students, B:Y = 3:4.
