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

Answer:

she use altogether flour is $1 \frac{3}{20}$ lb

Step-by-step explanation:

given data

flour to bake a vanilla cake = $\frac{2}{5}$ lb

flour to bake a chocolate cake =  $\frac{3}{4}$ 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 =  $\frac{2}{5}$ +  $\frac{3}{4}$

total flour is used =  $\frac{23}{20}$

she use altogether flour is $1 \frac{3}{20}$ lb

Answer 2

Answer: $\frac{23}{20}\ lb$ or $1\frac{3}{20}\ lb$

Step-by-step explanation:

For this exercise you need to add fractions.

To bake the vanilla cake, Penny used $\frac{2}{5}\ lb$ of flour and to bake the chocolate cake she used $\frac{3}{4}\ lb$ of flour.

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

$\frac{2}{5}\ lb+\frac{3}{4}\ lb$

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:

$\frac{2}{5}+\frac{3}{4}=\frac{4(2)+5(3)}{20}=\frac{23}{20}$

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:

$\frac{23}{20}\ lb=1\frac{3}{20}\ lb$