Answer:
3 
Step-by-step explanation:
Given
=
( cross- multiply )
4x =
× 28 = 14 ( divide both sides by 4 )
x =
=
= 3 
First off, let's change the format of the percentage to decimal.. so 35% is just 35/100 or 0.35 and 40% is 40/100 or 0.4 and so on.

now, whatever "x" amount is, we know that x + 10 must add up to "y". x + 10 = y, because both quantities added will give the mixture amount.
and whatever 0.35x + 4 = 0.37y, because both concentrated amounts must give the 37% of the mixture.

solve for "x", to see how much of the 35% solution will be needed.
what about "y"? well, x + 10 = y.
(-1,-10)(3,2)
slope = (2 - (-10) / (3 - (-1) = (2 + 10) / (3 + 1) = 12/4 = 3
y = mx + b
slope(m) = 3
(3,2)...x = 3 and y = 2
now we sub and find b, the y int
2 = 3(3) + b
2 = 9 + b
2 - 9 = b
-7 = b
so ur equation is : y = 3x - 7 or f(x) = 3x - 7
The speed to the island is x. The speed to return is x+5.
The distance is the same so, 2.5 multiplied by x = 2×(x+5).
It took 2.5 hrs to get there and 2 hrs to return. Now all we have to do is solve.
2.5*x = 2x + 10
.5x = 10
x=20
Therefore, the distance between islands is 2.5 × 20 = 50 miles.
hope this helps!
X/1 would equal -2- square root of 11 and x2 would equal -2 plus square root of 11