Question 1093565
I used c for current.
r*t=d
(26-c)*t=80
26*t-c*t=80

(26+c)*t=100
26*t-c*t=80
26*t+c*t=100
add
52t=180
t=180/52
t=3.46153846 hr
26*3.46153846+c*3.46153846=100
90.0+c*3.46153846=100
c*3.46153846=10.0
c=10.0/3.46153846
c=2.88888889 mph current
check
(26+c)*t=100
(26+2.88888889)*3.46153846=100
(28.8888889)*3.46153846=100
100.0=100

(26-c)*t=80
(26-2.88888889)*3.46153846=80
(23.1111111)*3.46153846=80
80.0=80
ok