William has $50. He wants to buy some t-shirts that cost $12 each. He also wants to have at least $10 left to buy lunch. What is the greatest number of t-shirts that William can buy and still have $10 for lunch?

The most t-shirts that he can buy is 3

Step-by-step explanation:

He has $50 and needs to have $10 for lunch. So take away the money for lunch and that leaves you with $40. Each t-shirt cost $12 so $40 divided by $12 is 3.333333333. But you can't buy a part of a t-shirt you the most t-shirt you can buy is 3

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