Question

Grandma has 3 1 /4 pounds of flour. She uses 1 2 /3 pounds of flour to make rolls for Thanksgiving dinner. How much flour does Grandma have left over?

Answer 1

Explanation:

`1 - ((1)/(4) + (2)/(3)) \\ = 1 - ( (3 + 8)/(12)) \\ = 1 - ( (11)/(12) ) \\ = (1)/(12)`

Answer 2

`1 (7)/(12)\; \sf pounds`

Explanation:

To find the amount of flour Grandma has left over, subtract the amount she used to make rolls from the original amount.

Given calculation:

`3 (1)/(4)-1 (2)/(3)`

Convert the mixed numbers into improper fractions by multiplying the whole number by the denominator of the fraction, adding this to the numerator of the fraction, and placing the answer over the denominator:

`\implies (3 * 4+1)/(4)-(1 * 3+2)/(3)`

`\implies (13)/(4)-(5)/(3)`

Change both fractions into equivalent fractions so both fractions have the same denominator:

`\implies (13 * 3)/(4* 3)-(5 * 4)/(3 * 4)`

`\implies (39)/(12)-(20)/(12)`

`\textsf{Apply the fraction rule} \quad (a)/(c)-(b)/(c)=(a-b)/(c):`

`\implies (39)/(12)-(20)/(12)=(39-20)/(12)=(19)/(12)`

Divide the numerator by the denominator:

`\implies 19 / 12 = 1 \; \sf remainder \; 7`

The solution as a mixed number is the whole number and the remainder divided by the denominator:

`\implies 1 (7)/(12)`