Question

Penny used 2/5 lb of flour to bake a vanilla cake. She used another 3/4 lb of flour to bake a chocolate cake. How much flour did she use altogether?

Answer 1

she use altogether flour is
`1 (3)/(20)` lb

Explanation:

given data

flour to bake a vanilla cake =
`(2)/(5)` lb

flour to bake a chocolate cake =
`(3)/(4)` lb

to find out

How much flour did she use altogether

solution

we know here flour use to make cake

so total flour is used = add both flour for vanilla and chocolate cake

total flour is used =
`(2)/(5)` +
`(3)/(4)`

total flour is used =
`(23)/(20)`

she use altogether flour is
`1 (3)/(20)` lb

Answer 2

Answer:
`(23)/(20)\ lb` or
`1(3)/(20)\ lb`

Explanation:

For this exercise you need to add fractions.

To bake the vanilla cake, Penny used
`(2)/(5)\ lb` of flour and to bake the chocolate cake she used
`(3)/(4)\ lb` of flour.

Then, the total flour she used can be found by solving this addition:

`(2)/(5)\ lb+(3)/(4)\ lb`

Since the denominators are different, you must find the Least Common Denominator (LCD).

Descompose the denominators into their prime factors and multipy the commons and non-commons with the highest exponent.

Then:

`5=5\\\\4=2*2=2^2`

`LCD=5*2^2=20`

So, the sum is:

`(2)/(5)+(3)/(4)=(4(2)+5(3))/(20)=(23)/(20)`

That improper fraction can be written as a mixed number.

When you divide the numerator 23 by the denominator 20 you get;

• A quotient of 1 (This will be the whole number).
• A remainder of 3 (This will be the numerator of the fraction).
• The denominator will not change.

Then:

`(23)/(20)\ lb=1(3)/(20)\ lb`