Answer:
A. 5cm, 6cm, 7cm
Step-by-step explanation:
3/8=2/4c+10
Multiply all terms by c and cancel:
3c/8=24+10c
(Simplify both sides of the equation)
3/8c=10c+24
(Subtract 10c from both sides)
3/8c−10c=10c+24−10c
−77/8c=24
(Multiply both sides by 8/(-77))
(8/−77)*(−77/8c)=(8/−77)*(24)
c=−192/77
To solve for the time it takes to travel a certain distance at a certain speed, use the formula,
time = distance / speed
Given that the entire journey takes four hours, add up the time it takes David to row upstream with that of him travelling downstream. This is mathematically represented as,
total time = time upstream + time downstream
4 = 3/(x - 1) + 3/(x +1)
Solving for x in the equation gives 2. Thus, David's speed in still water is 2 miles per hour.
Answer:
4
Step-by-step explanation:
A simple matter of using Pythagoras. The hypotenuse is the ladder, and one of the legs is the wall, and we have to figure out the value of the other leg.
The Pythagorean formuda is (hypotenuse = a): a² + b² = c² (b and c are the other sides)
applying the values: a = 5 and b or c is 3 (I'll put b = 3)
5² = 3² + c²
25 = 9 + c²
25 - 9 = c²
16 = c²
√16 = c
4 = c
c = 4