Curtis rides his bike 9 miles one way then turns around and rides back. On the return trip, his speed is increased 20% because the wind is at his back. Let s be his speed in miles per hour riding against the wind. What is an expression that represents his total time in hours riding there and back?

An expression would then be time = s / 9 + (s*1.2)/9 = 2.2s/9

Step-by-step explanation: Time is speed divided by distance. So time = s / 9 against the wind, and (s*1.2)/9 with the wind. An expression would then be time = s / 9 + (s*1.2)/9 = 2.2s/9

m∠a is 90°

m∠b is 40°

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