Question
Evaluate : $(9a − 7b) (3a − b)$
✓
Answer
$ (9a − 7b) (3a − b)$
$= 9a (3a − b) − 7b (3a − b)$
$= 27a^2 − 9ab − 21ab + 7b^2$
$= 27a^2 − 30ab + 7b^2$
$= 9a (3a − b) − 7b (3a − b)$
$= 27a^2 − 9ab − 21ab + 7b^2$
$= 27a^2 − 30ab + 7b^2$
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(a) $2: 5: 8$ $\quad$ (b) $5: 6: 8$
(c) $6: 8: 9$ $\quad$ (d) $5: 9: 16$
Q.2. If P, Q and R save one-half, one-third and one-fourth of their salaries respectively, what is the ratio of their expenditures ?
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(c) $5: 4: 6$ $\quad$ (d) $5: 8: 12$
Q.3. If P, Q and R receive increments of $20\%, 10\%$ and $15\%$ respectively in their salaries, what will be the ratio of their new salaries?
(a) $25: 16: 23$ $\quad$ (b) $25: 30: 42$
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