c. When adding unlike signs, subtract the smaller value from the larger and take
the sign of the larger. For example:
(+160)
+
(-100) =
+60
(-160)
+
(+100) =
-60
d. When multiplying or dividing, if the signs are alike the answer will always be
plus. If the signs are different, the answer will always be minus. For example:
(1)
Multiplication
+25
-25
-25
+25
x +5
x 5
x +5 x - 5
+125
+125
-125 -125
(2)
Division
_-5
_-5
_+5
_+5
+5 /+25
-5/-25
-5/+25
+5/-25
1-24. SAMPLE PROBLEMS
a.
Convert 140F to C:
5F
=
9C
+
160 (formula)
5(140)
=
9C
+
160 (substitution)
700
=
9C
+
160 (multiplication)
700 - 160 =
9C
(transposition)
540
=
9C
(subtraction)
60
=
C
(division)
Convert - 49F to C:
b.
5F
=
9C
+
160 (formula)
5(-49)
=
9C
+
160 (substitution)
-245
=
9C
+
160 (multiplication)
-245- l60
=
9C
(transposition)
MD0802
1-28
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