CPM Homework Help : MC2 Problem 7-21

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7-21.

Simplify each expression.

$- \frac { 9 } { 5 } \cdot \frac { 8 } { 15 }$
Hint (a):
Multiply the numerators together and the denominators together.
$-\frac{9(8)}{5(15)} = -\frac{72}{75}$
Answer (a):
$-\frac{24}{25}$

$\frac { 1 } { 5 } + ( - \frac { 2 } { 15 } ) - ( - \frac { 4 } { 9 } )$
Hint (b):
Find a common denominator.
$\frac{9}{45}+\left(-\frac{6}{45}\right)-\left(-\frac{20}{45}\right)$

$- \frac { 4 } { 8 } \cdot \frac { 3 } { 7 } \cdot ( - \frac { 2 } { 5 } )$
Hint (c):
Multiply, see (a) for help.

$\frac { 3 } { 5 } \cdot ( - \frac { 2 } { 7 } ) + ( - \frac { 5 } { 7 } ) ( \frac { 3 } { 10 } )$
Hint (d):
Multiply the terms, then find the common denominator.
Answer (d):
$-\frac{27}{70}$

$- 8 \frac { 1 } { 9 } + 3 \frac { 5 } { 6 }$
Hint (e):
Make improper fractions, then find the least common denominator.

$2 \frac { 1 } { 2 } \cdot 4 \frac { 1 } { 5 }$
Hint (f):
Convert the mixed numbers into improper fractions before multiplying.
Answer (f):
$10\frac{1}{2}$

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