Page 115 - ArithBook5thEd ~ BCC

Solution. Subtraction comes first in the left-to-right order. Rewriting 2 as 10 ,we have
5
10 3 1 7 1
" #
− + = +
5 5 2 5 2
14 5
= + (LCD = 10)
10 10
19
=
10
9
=1 .
10

3 1
" #
Example 137. Calculate 1 − + .
5 2
Solution. The parentheses force us to do the addition first. Rewriting 3 and 1 with the LCD 10, we
5 2
have
" #
6 5 11
1 − + =1 −
10 10 10
10 11
= −
10 10
1
= − .
10

" # 2
2 2 1
Example 138. Calculate − +1 · .
3 3 10
4
2 2
Solution. We evaluate the expression with an exponent first: (− ) = .Then we do the multiplication
3
9
(converting the mixed number to an improper fraction). Additioncomes last.
2 2 1 4 2 1
" # 2
− +1 · = +1 ·
3 3 10 9 3 10
4 5 1
= + ·
9 3 10
4 5
= +
9 30
4 1
= + (cancelling 5)
9 6
8 3
= + (LCD = 18)
18 18
11
= .
18

1 2 1 " 1 #
Example 139. Calculate 1 · +1 ÷ −1 .
4 3 6 2

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