Four friends’ typing speeds are shown. Who is the fastest? Monica: 10 words in 1 4minute Rachel: 55 words in 5 6minute Charlie: 42 words in 3 4minute Daniel: 25 words in 1 2minute

a) 7x=7

step-by-step explanation:

70.30

step-by-step explanation:

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