CPhill

There's an easy way to determine this, rarinstraw

Set the rectangles up in ratios of long side / short side  to  long side / short side   .... we have

16.4 / 10.8  =  10.25 / 6.75       cross-multiply

16.4 (6.75)  =  10.8 ( 10.25)     ???

110.7   =  110.7

Since the cross-products are equal....the rectangles are similar

If we compare  long side to long side....we have

16.4 / 10.25  =     the ratio of the larger rectangle to the smaller  =  1.6  : 1

[The same ratio would be found by comparing short side to short side ]

lim  x →3   [  x^2 - 2x - 3 ] / [ x  -3  ]              factor the numerator

lim x → 3     [ (x + 1) (x - 3) / [ x - 3 ]

lim x →  3       x +  1       =     4

3/9    = 1/3       →   1 cupcake every 3 minutes  =    1/3 cupcake every 1 minute

Let the regular price = P

So

P - .20 P   = 60

.80 P  = 60      divide by sides by .80

P  = $75

L^-.5 = 2C^-.5   square both sides

L^-1  = 4C^-1     and we can write

1 / L   = 4/C   and this equals

L / 1  = C / 4     so

L  = C /4      [ C ≠ 0]

5(c-6)+c =c+11+24      simplify this

5c - 30  + c  = c + 11 + 24

6c - 30  = c + 11 + 24

 -c  +30    -c                 +30

5c        =      11 + 24 + 30

5c   =   65         divide both sides by 5

c  = 13

Assuming compound interst, we have

A = 1000 ( 1 + .05)^7  = $1407.10    after 7 years

B + 7 = 21

     -7     -7

B   =  14

Nice, OP  !!!!

( r + 9s) ^2   =

(r + 9s) ( r + 9s)  =

r^2 + 9rs + 9rs  + 81s^2  =

r^2 + 18rs + 81s^2