a man is now 9 times as old as his daughter. in four years time he'll be five times as old as his daughter. what are their present ages

The father is 36 right now and the son is 4

Step-by-step explanation: 9x4 is 36 and 36/9=4.

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