ElectricPavlov

x is th amount she starts with in her wallet.

she spends 1/5 of x     1/5 x     so now she has 4/5x LEFT

of what she has LEFT , she spends 1/5   

   1/5  * 4/5x   

so all totalled she spent    1/5x   +    1/5 * 4/5 x   =36

                                          1/5x  + 4/25x =36

                                           5/25 x + 4/25 x = 36

                                           9/25 x = 36

                                                  x =36 (25/9) = original amount = $100.

These questions are always a bit misleading and often result in multiple answers....

from 4 to 8   would be a 100% increase.....right?

from 4 to 10 would be a 150% increase....       6/4 x 100 = 150%

20/25   x 100% = 80%

How about   A    Take a look....     answer   A   B   E

Price per month would be   $5976/12 months =  $ 498/month

    she paysonly 30% of this

         .3 (498) = $149.40 per month       (She IS lucky !)

4/3 pi r^3   is volume of a sphere      usin p = 3.14

softball (the larger of the two) = 4/3 pi (1.9)^3           (make sure you use RADIUS....the Q gives DIAMETER !!!)

        4/3  (3.14) (1.9)^3   in³   Use calculator to find volume of softball....

then find the volume of the BASEball the same way except  r = 1/2 d = 1.5 inches for baseball

    then find the difference between the two    ........    difference will be in^{3   (don't forget units in your answers !)}

I know , MS...but this is simply looking at the picture to see which points are on any line.....you can do this

      B is correct....any others?  (yes)

Great illustration , Omi !!!

9^6=9*9*9*9*9*9

   but  9*9*9*9*9*9  = 531441    (snigger)   

200 liters of 75% = .75 (200) = 150 gallons of acid

.90 x   +  .50(200-x)  = 150

.9x   + 100 - .5x = 150

.4x = 50

x = 90% solution = 125 gallons

200-x = 50% solution = 200-125 = 75 gallons of 50% solution