Solve 31/5div8/5*21/10

$$3 \frac { 1 } { 5 } \div \frac { 8 } { 5 } \times 2 \frac { 1 } { 10 }$$

Evaluate

$$\frac{21}{5}=4.2$$

Solution Steps

Divide \frac{3\times 5+1}{5} by \frac{8}{5} by multiplying \frac{3\times 5+1}{5} by the reciprocal of \frac{8}{5}.

$$\frac{\left(3\times 5+1\right)\times 5}{5\times 8}\times \frac{2\times 10+1}{10}$$

Cancel out 5 in both numerator and denominator.

$$\frac{1+3\times 5}{8}\times \frac{2\times 10+1}{10}$$

Multiply 3 and 5 to get 15.

$$\frac{1+15}{8}\times \frac{2\times 10+1}{10}$$

Add 1 and 15 to get 16.

$$\frac{16}{8}\times \frac{2\times 10+1}{10}$$

Divide 16 by 8 to get 2.

$$2\times \frac{2\times 10+1}{10}$$

Multiply 2 and 10 to get 20.

$$2\times \frac{20+1}{10}$$

Add 20 and 1 to get 21.

$$2\times \frac{21}{10}$$

Express 2\times \frac{21}{10} as a single fraction.

$$\frac{2\times 21}{10}$$

Multiply 2 and 21 to get 42.

$$\frac{42}{10}$$

Reduce the fraction \frac{42}{10} to lowest terms by extracting and canceling out 2.

$$\frac{21}{5}$$

Factor

$$\frac{3 \cdot 7}{5} = 4\frac{1}{5} = 4.2$$