H = 2f / (m+1)
[multiply by (m+1)]
h(m+1) = 2f
[divide by 2]
f = (h (m + 1)) / 2
3b / (b+2) = 12 / (b+2)
[multiply by (b+2)]
3b = 12
[divide by 3]
b = 4
3 / (6x + 1) / 2 = 8 / (x + 4) / 3
[multiply both denominators to mike one denominator]
3 / 8(6x+1) = 8 / 3(x+4)
[expand brackets]
3 / (48x + 8) = 8 / (3x + 12)
[multiply by (48x + 8)]
3 = 8(48x + 8) / (3x+12)
[multiply by (3x+12)]
3(3x +12) = 4(48x + 8)
[simplify]
9x + 36 = 192x + 32
173x = 4
x = 4 / 173
log(3x) = log(2x-4)
taking antilog of both sides:
3x = 2x - 4
3x - 2x = -4 [subtracting 2x from both sides]
x = -4
and we're done already!
You multiply the length, the width, and the height. You can multiply them in any order, and you would still get the same answer.
Commonsense you do math in your mind