Page 42 - Math Course 1 (Book 2)

Linear Equations: Addition and Subtraction

Write and Solve an Equation
Your Turn!

Examples Solve by Adding or Subtracting

2 5
Write an equation for the problem. Solve + y =
Then solve the equation. 3 6

Fourteen more than a number is equal to A. 1
twenty-seven. Find this number. 1
B. – 6
Fourteen more than a number is equal to twenty-seven. 1
C.
14 + n
= 27
14 + n = 27 6
3
D.
14 + n = 27 Original equation 2
14 + n – 14 = 27 – 14 Subtract 14 from each side. Answer

n = 13
Answer 14 – 14 = 0
and 27 – 14 = 13

Write and Solve an Equation Write and Solve an Equation

Examples Twelve less than a number is equal to negative
twenty-f ve. Find the number.

HISTORY A. –37
B. 37
The Washington Monument C. 13
in Washington, D.C., was built D. –13
in two phases. During the f rst
phase, the monument was built
to a height of 152 feet. During Answer
the second phase, the additional
construction resulted in the mon-
ument’s f nal height of 555 feet.
How much of the monument
was added during the second
construction phase? Write an Real World Example
equation to solve the problem.
The Sears Tower was built in 1974. The height to the
The f rst height plus the additional
Words Sky Deck is 1353 feet. The actual recorded height is
height equals 555 feet. 1450 feet. In 1982, they added twin antenna tow-
Variables Let a = the additional height. ers, which do not count for the record, for a total
structure height of 1707 feet. How tall are the twin
The first height plus the additional height equals 555.
antenna towers?
152 + a = 555
152 + a = 555 Original equation A. 3157 feet
B. 257 feet
Subtract 152 from C. 300 feet
152 + a – 152 = 555 – 152
each side. D. 150 feet
152 – 152 = 0 and
a = 403 Answer
555 – 152 = 403
There were 403 feet added to the
Answer Washington Monument during the
second construction phase

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