Question 250284
D=RT
LET B=THE SPEED OF THE BOAT & C=THE SPEED OF THE CURRENT.
105=(B+C)10
105=(B-C)70
10(B+C)=70(B-C)
10B+10C=70B-70C
10B-70B=-70C-10C
-60B=-80C
B=-80C/-60
B=1.333C
105=(1.333C+C)10
105=2.333C*10
105=23.33C
C=105/23.33
C=4.5 MPH. FOR THE CURRENT.
1.333*4.5=6 MPH. FOR THE SPEED OF THE BOAT.
PROOF:
105=(1.333*-4.5-4.5)70
105=(6-4.5)*70
105=1.5*70
105=105