Answer:
3n+7=16
Step-by-step explanation:
3(3)+7=16
9+7=16
16=16
The second one is wrong(x=18)
Answer:
The speed in still water is 5 miles per hour.
Step-by-step explanation:
distance with current = 90 miles
distance against current = 10 miles
speed in still water = s
speed of current = 4 mph
speed with current = s + 4
speed against current = s - 4
time = t
speed = distance/time
distance = speed * time
With current:
90 = (s + 4) * t
Against the current:
10 = (s - 4) * t
We have a system of equations:
90 = (s + 4) * t
10 = (s - 4) * t
90 = ts + 4t
10 = ts - 4t
Subtract the second equation from the first equation.
80 = 8t
10 = t
t = 10
10 = t(s - 4)
10 = 10(s - 4)
1 = s - 4
s = 5
Answer: The speed in still water is 5 miles per hour.
Answer:
Step-by-step explanation:
<u>Given system:</u>
<u>Multiply the first equation by 7 and add up the equations:</u>
- -7x + 7y + 7x + 3y = 7*8 - 16
- 10y = 40
- y = 4
<u>Find y:</u>
