Answer: the speed of the current is 9 mph.
Step-by-step explanation:
Let x represent the speed of the current.
A boat can travel 21 mph in still water. If it travels 270 miles with the current. It means that the total speed with which the boat travelled with the current is (21 + x) mph.
Time = distance/speed
Time spent by the boat in travelling 270 miles is
270/(21 + x)
In the same length of time, it travels 108 miles against the current. It means that the total speed with which the boat travelled against the current is (21 - x) mph.
Time = distance/speed
Time spent by the boat in travelling 108 miles is
108/(21 - x)
Since the time is the same, then
270/(21 + x) = 108/(21 - x)
270(21 - x) = 108(21 + x)
5670 - 270x = 2268 - 108x
108x + 270x = 5670 - 2268
378x = 3402
x = 3402/378
x = 9
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Answer:
a. 1:4.5, 5. the length is 8. c. first length * 8 = 88. Add lengths = 8+11/12 = 19/12
Step-by-step explanation:
Answer:
369
Step-by-step explanation:
g(f(x)) simply means to put the whole expression of function f(x) into the place of "x" in g(x).
and to find the functional value for a specific x we just need to calculate functional value for f(x) and use that result as input for g(x).
f(6) = 8×6 + 5 = 48 + 5 = 53
and now
g(53) = 7×53 - 2 = 371 - 2 = 369
to check we do the general functional substitution :
g(f(x)) = 7×(8x+5) - 2 = 56x + 35 - 2 = 56x + 33
g(f(6)) = 56×6 + 33 = 336 + 33 = 369
correct
