ElectricPavlov

https://web2.0calc.com/questions/can-somebody-please-help

30 km / 5hr = 6 km/hr

30 km / 6.25hr = 4.8 km/hr

in still water    ( 6+ 4.8)/2 = 5.4 km hr in still water

current =   6 - 5.4 = .6 km/hr        or     5.4 - 4.8 = .6 km/hr

6^(3t - 1) = 36^t.

               = (6²)^t

so equate the exponents

3t-1 = 2t

t = 1

You got it set up correctly....now cross multiply to get    x^2 + 10x - 144 = 0 

                          x = 8

l  = 1/3 w

perimeter  =   1/3 w   + 1/3 w  + w + w = 24

                        2 2/3 w = 24

                              w = 9     then   l = 3         area = l * w =   27 cm²

Rectangle area = l x w  =   4 x 2 = 8 units²

    SUBTRACT area of two circles    2*    pi (1^2)      to get final answer

8(2x - 4) = -4(-4x + 8)      Expand L and R sides

16x-32   = 16x -32

0 = 0                               SO ANY value of 'x' will be true

Inscribed angle E encompasses twice as many degrees of arc

2 *62   - 64   = CD

= 60^o

sin 2theta = 2 sin cos

                 = 2 ( 3/5)(4/5) = 24/25

cos 2theta = cos^2 - sin^2

                  = (4/5 )^²  - (3/5)^2   =  16/25 - 9/25 =  7/25

SImilar for alpha....use double angle identities .....           tan(2alpha) =  2 tan / (1- tan²  ) .

Sum of boys /5   = 9.8               Sum of girls/15 = 10.2

S_b  = 5* 9.8 = 49                         Sg  = 153

(49 + 153)/  (5+15) = 10.1 years