10. sue has a boat that would go 9 miles per hour in still water. she travels downstream for a
certain distance and then back upstream to where she stared. sue notices that it takes her 4
hours to travel upstream against the river, and only 2 hours to travel downstream with the
river. the rivers speed is r miles per hour. write and solve for r.

Step-by-step explanation:

In downstream, the speed of the boat will be (9 + r) miles per hour and in upstream the speed of the boat will be (9 - r) miles per hour.

Ratio of the speed in downstream to the speed in upstream is (9 + r):(9 - r).

Hence, the ratio of the time taken by the boat to cover the distance in downstream to upstream is  (9 - r):(9 + r).

x =-.20752

step-by-step explanation:

4^(x+2)=12

4^(x+2)=12

take the log base 4 on each side

log 4 (4^(x+2) = log 4(12)

we know log b(a^y) = y log b (a)

(x+2) log 4(4) = log 4 (12)

x+2 = log 4 (12)

we know   logb c = loga c/loga b

we want to convert to base 10   so a = 10

by default, we do not write the 10   c = 4   and b = 10

log4 10 = log 12/log 4

log4 10 = log 12/ log 4

x+2 = log 12/ log 4

subtract 2 from each side

x +2 -2 = log 12/ log 4 -2

x = 1.79248125 -2

x =-.20752

try soting them out first

step-by-step explanation: