First, find the number of females in the class. 
Then, just write the ratio. 
Answer:
f =38
Step-by-step explanation:
f-3/4=5/6
f-3×6=5×4
f-18 =20
f =20+18
f =38
15. x ≤ -24
x + 19 ≤ -5
x ≤ -24
16. z > -12
3z > -36
z > -12
17. 185 + c > 410; c > 225
18. C.
x - 6 ≥ 1
x ≥ 7
Let, length and breadth of rectangle is L and B respectively.
It is given that :
The length rectangle is 4 cm more than 3 times the width of the rectangle.
L = 3B + 4 ......1 )
Also, area of square = area of the rectangle + 66
L² = LB + 66
Putting value of L from
L² = ( 3B + 4 )( B ) + 66
L² = 3B² + 4B + 66
( 3B + 4 )² = 3B² + 4B + 66
9B² + 16 + 24B = 3B² + 4B + 66
6B² + 20B - 50 = 0
3B² + 10B - 25 = 0
3B² + 15B - 5B -25 = 0
3B( B + 5 ) -5( B + 5 ) = 0
B = 5/3 units
L = 3( 5/3 ) + 4
L = 5 + 4 = 9 units
Hence, this is the required solution.
Answer:
rearrange them properly to get
x-y=7
-3x+y=12
( by elimination method)
x-y = 7
-3x+y=
(x+ –3x) + (–y+y) = (7+12)
-2x+0= 19
x= -9.5
from eqn(i)
x-y=7
-9.5 - y=7
-y=16.5
y= -16.5
