Answer:
Step-by-step explanation:
let the speed of one plane=x
speed of other plane=x+80
time=4 hrs
then 4x+4(x+80)=3800
4x+4x+320=3800
8x=3800-320
or 8x=3480
x=435
speed of one plane=435 m/h
speed of other plane=435+80=515 m/h
2.
Let he walks x hrs
then he take a taxi for 2-x hrs
4x+(2-x)50=31
4x+100-50x=31
-46x=-69
so he walks 3/2 hrs=1.5 hrs
travels by taxi=2-1.5=0.5 hrs
distance traveled by taxi=0.5×50=25 miles
the answer is 16
8^(4/3) can be written in different ways. You can first simplify it by breaking the exponents down into 1/3 and 4. You can write it as (8^1/3)^4 (it still means the same thing). When you raise something to the one over something fraction, the denominator tells you what the root is. Because it says 1/3, it means that you're finding the cube root of something. So you can rewrite it as (3√8)^4 (the three should be sitting on top of the sign to signify that it's cube root). You then just solve from there. The cube root of 8 is 2 (2*2*2=8) so it'll simplify to (2)^4. You then solve it from there and get 16 as your answer (2*2*2*2=16).
3 is 13 more than 10, and 3 is 30% of 10, so 30% im pretty sure
![\bf \cfrac{x}{4x+x^2}\implies \cfrac{\begin{matrix} x \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}}{\begin{matrix} x \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~(4+x)}\implies \cfrac{1}{4+x}\qquad \{x|x\in \mathbb{R}, x\ne -4\}](https://tex.z-dn.net/?f=%5Cbf%20%5Ccfrac%7Bx%7D%7B4x%2Bx%5E2%7D%5Cimplies%20%5Ccfrac%7B%5Cbegin%7Bmatrix%7D%20x%20%5C%5C%5B-0.7em%5D%5Ccline%7B1-1%7D%5C%5C%5B-5pt%5D%5Cend%7Bmatrix%7D%7D%7B%5Cbegin%7Bmatrix%7D%20x%20%5C%5C%5B-0.7em%5D%5Ccline%7B1-1%7D%5C%5C%5B-5pt%5D%5Cend%7Bmatrix%7D~~%284%2Bx%29%7D%5Cimplies%20%5Ccfrac%7B1%7D%7B4%2Bx%7D%5Cqquad%20%5C%7Bx%7Cx%5Cin%20%5Cmathbb%7BR%7D%2C%20x%5Cne%20-4%5C%7D)
if you're wondering about the restriction of x ≠ -4, is due to that would make the fraction with a denominator of 0 and thus undefined.
