Recall your d = rt, distance = rate * time.
let's say the boat has a still water rate of "b", and the current has a a rate of "c", ok.... when the boat is going upstream, is not really going "b" fast, is going slower at "b - c", due to the current going in the opposite direction.
when the boat is coming downstream, is not going "b" fast either, is going faster, is going "b + c", due to the current adding speed to it.
we know the trip up was 108 kms, thus the return trip is also 108 kms.

and surely you know how much that is.
what's the boat's speed? well, 36 + c = b.
The students = 18/1 x 12
the students = 18 x 12
the students = 216
There are 216 students attending the school
Answer:
4
Step-by-step explanation:
The graph is moved up by 4, that is why it says +4 in the equation
What do you want to calculate?
CALCULATE IT!
Solve
Graph
Lesson
Problem:
Solve
x
+
2
y
=
−
6
;
3
x
+
8
y
=
−
20
Steps:
I will solve your system by substitution.
(You can also solve this system by elimination.)
x
+
2
y
=
−
6
;
3
x
+
8
y
=
−
20
Step: Solve
x
+
2
y
=
−
6
for x:
x
+
2
y
+
−
2
y
=
−
6
+
−
2
y
(Add -2y to both sides)
x
=
−
2
y
−
6
Step: Substitute
−
2
y
−
6
for
x
in
3
x
+
8
y
=
−
20
:
3
x
+
8
y
=
−
20
3
(
−
2
y
−
6
)
+
8
y
=
−
20
2
y
−
18
=
−
20
(Simplify both sides of the equation)
2
y
−
18
+
18
=
−
20
+
18
(Add 18 to both sides)
2
y
=
−
2
2
y
2
=
−
2
2
(Divide both sides by 2)
y
=
−
1
Step: Substitute
−
1
for
y
in
x
=
−
2
y
−
6
:
x
=
−
2
y
−
6
x
=
(
−
2
)
(
−
1
)
−
6
x
=
−
4
(Simplify both sides of the equation)
Answer:
x
=
−
4
and
y
=
−
1