ElectricPavlov

fat ingredients = final fat amount

.10x       +   .35(15-x)     =      .20 (15)     

            solve for 'x' the amount of 10% to use    then 35% amount = 15-x

LCM  4   5   8  = 40   convert to denominator 40

yellow = 50/40      green = 48/40       blue = 35/40

total ( 50 + 48 + 35) / 40 = 133/40    

Now use 3/4 gal of each  (  3/4  is  30 /40 )

133/40 -      3 * 30/40    =   43/40   =   1  3/40 gal paint left

Original    area    2  ( 6*2 + 6*9 + 2*9) = 168 in^2

double h   (from 9 to 18) area    2 ( 6*2 + 6*18 + 2*18) = 312 in^2               Fixed typo

double w   ( from 2 to 4 ) area   2 ( 6*4 + 6*9 + 4*9) = 228 in^2

Doubling w will use   (312 - 228) = 84 in2 less material

Interior angles of triangle sum to 180

(11x-9) + 6x-2  + 72 = 180        solve for 'x'

and

30 + ( 5y-8) + 11x-9 = 180       (use the value of x yo found above)   solve for 'y'

Just use calculator

3.8646/.0076 = 508.5

square base      9*9

 PLUS 4  triangle sides (area = 1/2 b*h)      4  *    1/2* 9 * 9.2             Add the reds for final answer......

Original area   2 x 5 = 10 cm²

Now double the base from 5 to 10

    New area =   2 x 10 = 20  cm²     =    2 times the original area    

Original area    10  x   10 = 100 mm²

  triple the lengths

        30  x 30 = 900 mm²          New area is 9 times original

8.12342e-07    = 8.12342 X 10^{-7           edited....forgot the  ' - ' sign}

Nearest dollar amount = $ 25

.20 * $25 = $ ............    tip amount