# What is 1/21-13/8?

How much is 121 minus 138. Step by step solution expressed as a proper or improper fraction, mixed number and decimal form.

• - 265168
• - 1 97168
• 1.5774 (rounded to 4 decimals)

## Step by step solution

Subtract

121 - 138 = - 265168

1. ### Find common denominator by finding the Least Common Multiple(LCM)

Multiples of 21 are   21, 42, 63, 84, 105, 126, 147, 168 ....etc

Multiples of 8 are   8, 16, 24, 32, 40, 48, 56, 64, ..., 168 ...etc

The LCM of 21 and 8 is 168. So, the common denominator of 121 and 138 is 168. Now change the fractions into equivalent fractions with common denominator

• 121 - 138
• 1 * 821 * 8 - 13 * 218 * 21
• 8168 - 273168
2. ### Subtract

• 8168 - 273168
• 8 - 273168
• - 265168

Subtract the numerators and place the difference over the common denominator.

Simplify

• - 265168
• - 1 97168
1. ### Reduce fraction to its lowest terms

The greatest common divisor of 265 and 168 is 1, the fraction - 265168 cannot be further simplified or reduced to lowest terms

2. ### Convert improper fraction - 265168 to mixed number

• - 265168
• - 1 97168

265 divided by 168 is 1 with a remainder of 97