Speed, S = Distance (d) / Time (t) => S= d/t => t= d/S
Let the speed of boat in still water be x mph
Resulting speed upstream = x-4 mph for a distance of 30 miles
Resulting speed downstream = x-4 mph for a distance of 50 miles
Time taken in both distances is equal.
Therefore,
30/(x-4) = 50/(x+4) => 30(x+4) = 50(x-4) => 30x+120 = 50x-200 => 120+200 = (50-30)x => 20x = 320 => x=320/20 = 16 mph
The speed of boat in still water is 16 mph.
It’s D because the number that have an (x) is a COEFFICIENT and I hope it helps :)
Answer: 
Step-by-step explanation:
Given
Radius of cylinder 
The height of the cylinder is 
The surface area of a cylinder is 
If only the outer is considered then, the area required is

Answer:
t = 28 minutes
Step-by-step explanation:
Last Saturday, Camila practiced her dance routines for her upcoming competition. She spent some time practicing her tap routine, and then she spent 17 minutes practicing her hip-hop routine. In all, she practiced for 45 minutes. Let t be the number of minutes that Camila practiced her tap routine. Write and solve an equation to find t.
45 minutes = Number of minutes for hip-hop routine + Number of minutes for tap dance
The equation is given as
45 = 17 + t
Solving for t
t = 45 - 17
t = 28 minutes
Shes spent 28 minutes tap dancing