Question

A mixed fraction, expressed in lowest terms, is in the form a b/c

The fraction is halved and then 3/4 is added

The result is 1 9/20

find the values of a, b, and c

Answer 1

a = 1

b = 2

c = 5

Explanation:

Given

Mixed fraction: a b/c

Result after arithmetic operations = 1 ⁹/20

Required.

Find a, b, c

From the question, the fraction is halved. This is represented as follows

a b/c ÷ 2

= a b/c * ½

Then, ¾ is added. This is represented by

a b/c * ½ + ¾

The result is 1 ⁹/20. This is represented by

a b/c * ½ + ¾ = 1⁹/20

Convert mixed fraction to improper fraction

a b/c * ½ + ¾ = 29/20

Subtract ¾ from both sides

a b/c * ½ + ¾ - ¾ = 29/20 - ¾

a b/c * ½ = (29 - 15)/20

a b/c * ½ = 14/20

a b/c * ½= 7/10

Multiply both sides by 2

2 * a b/c * ½= 7/10 * 2

a b/c = 14/10

a b/c = 7/5

Convert mixed fraction to improper fraction

a b/c = 1⅖

By comparison,

a = 1

b = 2

c = 5

Answer 2

The answer is actually a proper fraction = 7/20

Explanation:

A mixed fraction is expressed as : a b/c

Let the mixed fraction be represented by Y

a) The fraction is halved

= Y ÷ 1/2 = Y/ (1/2)

In mathematics, when we divide a number by a fraction, the number is multiplied by the reciprocal of the fraction.

Y × 2 = 2Y

b) Then 3/4 is added

= 2Y + 3/4

c)The result is 1 9/20

2Y + 3/4 = 1 9/20

Converting the mixed fraction to improper fraction, we have

1 9/20 = (20 × 1) + 9/ 20 = 29/20

Therefore,

2Y + 3/4 = 29/20

2Y = 29/20 - 3/4

The Lowest common multiple of the right hand side = 20

2Y = (29 - 3×5)/ 20

2Y = 29 - 15/20

2Y = 14/20

2Y = 7/10

To find Y , we cross multiply

2Y × 10 = 7

20Y = 7

Y = 7/20

Therefore, the mixed fraction represented by Y is actually a proper fraction = is 7/20