And 3
1 1/3
7. Felicia. Grace, Joan and Marilyn share a sum of money. Felicia and Grace take
of the
sum of money respectively. After Felicia and Grace have taken their share, Joan takes of the
remaining money. After Joan has taken her share, Marilyn takes all of the remaining money. If
Marilyn's share is $75, find the original sum of money.
[3]

the answer is 13

step-by-step explanation:

5*5=25

12*12=144

25+144=169

169^2=13

hello from mrbilldoesmath!

answer:

(7 x + 6 y) (49 x^2 - 42 x y + 36 y^2)

discussion:

the trick is to recognize that 343 = 7^3 and 216 = 6^3 and, in general,

a^3 + b^3 =   (a + b) (a^2 - a b + b^2).

in our case

343x^3+216y^3   =   (7x)^3 + (6y)^3

so take a = 7x and b = 6y in the above equation to get the answer.

you,

mrb