If m = 4, n = 9 and r = 16., evaluate \;m/n - 1\;7/9 + \;n/r

Correct Answer is : - 3748\;37/484837

Correct Answer is : - 3748\;37/484837

Test Index

WAEC Mathematics 2015 Paper

Question : 10

Total: 45

\;\frac{m}{n}

\;\frac{7}{9}

\;\frac{n}{r}

Solution:

Concept:

Substitute the given values into the expression and simplify the resulting fractions.

Explanation:

Given

m=4

n=9

, and

r=16

The expression is

\frac{m}{n} - 1\frac{7}{9} + \frac{n}{r}

Substitute the values:

\frac{4}{9} - 1\frac{7}{9} + \frac{9}{16}

Convert the mixed number:

1\frac{7}{9} = \frac{16}{9}

So the expression becomes

\frac{4}{9} - \frac{16}{9} + \frac{9}{16}

Use LCM of

9

and

16

, which is

144

\frac{4}{9} - \frac{16}{9} + \frac{9}{16} = \frac{64 - 256 + 81}{144}

Simplify the numerator:

64 - 256 + 81 = -111

Thus we get

\frac{-111}{144}

Reduce by dividing numerator and denominator by

3

\frac{-111}{144} = -\frac{37}{48}

Answer:

-\frac{37}{48}

, which is option D.

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