20 x
+
20 y
= 1 (1)
40 x
+
10 y
= 1 (2)

40 x

40 y
=  2
40 x
+
10 y
= 1
Adding them up: ^{30}
y
=  1 ⇒ 30 = y
Substitute y = 30 into (1):
20
x
+^{20}
30
= 1 ⇒^{20}
x
= 1 ^{2}
3
⇒^{20}
x
=^{1}
3
20 x
+
20 y
= 1 (1)
40 x
+
10 y
= 1 (2)

40 x

40 y
=  2
40 x
+
10 y
= 1
Adding them up: ^{30}
y
=  1 ⇒ 30 = y
Substitute y = 30 into (1):
20
x
+^{20}
30
= 1 ⇒^{20}
x
= 1 ^{2}
3
⇒^{20}
x
=^{1}
3
⇒ x = 60
20 x
+
20 y
= 1 (1)
40 x
+
10 y
= 1 (2)

40 x

40 y
=  2
40 x
+
10 y
= 1
Adding them up: ^{30}
y
=  1 ⇒ 30 = y
Substitute y = 30 into (1):
20
x
+^{20}
30
= 1 ⇒^{20}
x
= 1 ^{2}
3
⇒^{20}
x
=^{1}
3
⇒ x = 60
Hence, Pipe 1 can finish filling the pool alone in 60 minutes
while Pipe 2 can do it in 30 minutes.
When Usain Bolt ran 9.68 seconds in the final event of the
100 m dash at a track meet, it was found out that he ran in
the wind’s direction. Minutes earlier, in the 100 m dash
eliminations, he ran directy against the wind and clocked
9.82 seconds. If the wind had a constant speed, what is
Usain Bolt’s average speed?
When Usain Bolt ran 9.68 seconds in the final event of the
100 m dash at a track meet, it was found out that he ran in
the wind’s direction. Minutes earlier, in the 100 m dash
eliminations, he ran directy against the wind and clocked
9.82 seconds. If the wind had a constant speed, what is
Usain Bolt’s average speed? Solution: Let x be his speed, y be the wind’s speed
When Usain Bolt ran
9.68 seconds in the final event of the
100 m dash at a track meet, it was found out that he ran in
the wind’s direction . Minutes earlier, in the 100 m dash
eliminations, he ran directy against the wind and clocked
9.82 seconds. If the wind had a constant speed, what is
Usain Bolt’s average speed?
Solution: Let x be his speed, y be the wind’s speed
x + y =
100 9 . 68
When Usain Bolt ran 9.68 seconds in the final event of the
100 m dash at a track meet, it was found out that he ran in
the wind’s direction. Minutes earlier, in the 100 m dash
eliminations, he ran directy against the wind and clocked
9.82 seconds . If the wind had a constant speed, what is
Usain Bolt’s average speed?
Solution: Let x be his speed, y be the wind’s speed
x + y =
100 9 . 68
x  y =
100 9 . 82
When Usain Bolt ran 9.68 seconds in the final event of the
100 m dash at a track meet, it was found out that he ran in
the wind’s direction. Minutes earlier, in the 100 m dash
eliminations, he ran directy against the wind and clocked
9.82 seconds. If the wind had a constant speed, what is
Usain Bolt’s average speed?
Solution: Let x be his speed, y be the wind’s speed
x + y =
100 9 . 68
x  y =
100 9 . 82
Adding the two equations: 2 x =^{100}
9 . 68
+^{100}
9 . 82
When Usain Bolt ran 9.68 seconds in the final event of the
100 m dash at a track meet, it was found out that he ran in
the wind’s direction. Minutes earlier, in the 100 m dash
eliminations, he ran directy against the wind and clocked
9.82 seconds. If the wind had a constant speed, what is
Usain Bolt’s average speed?