John is cooking cupcakes. the recipe calls for 3 3/10 cups of flour. He accidentally put 3 5/8 cups. How many cups did he add?

Answer 1

To solve this problem, we need to subtract the correct amount of flour from the amount John actually put.

The correct amount of flour is 3 3/10 cups.
To convert the mixed number to an improper fraction, we multiply the whole number (3) by the denominator (10) and add the numerator (3) to get 33/10.

John put 3 5/8 cups of flour.
To convert the mixed number to an improper fraction, we multiply the whole number (3) by the denominator (8) and add the numerator (5) to get 29/8.

Now we can subtract: 29/8 - 33/10.
To subtract fractions with different denominators, we need to find the least common multiple (LCM) of the denominators (8 and 10), which is 40.

Next, we convert the fractions to have a common denominator of 40.
(29/8) x (5/5) = 145/40
(33/10) x (4/4) = 132/40

Now we can subtract: 145/40 - 132/40 = 13/40

Therefore, John added 13/40 cups of flour by mistake.