$\mathbf{a})$

$60\frac{\text{m}}{\text{min}}=60\cdot \frac{1\text{m}}{60\text{s}}=1\frac{\text{m}}{\text{s}}$

 

$\mathbf{b})$

$300\frac{\text{cm}}{\text{s}}=300\cdot \frac{0,01\text{m}}{1\text{s}}=3\frac{\text{m}}{\text{s}}$

 

$\mathbf{c})$

$36\frac{\text{km}}{\text{h}}=36\cdot \frac{1000\text{m}}{3600\text{s}}=10\frac{\text{m}}{\text{s}}$

 

$\mathbf{d})$

$20\frac{\text{m}}{\text{s}}=20\cdot \frac{0,001\text{km}}{\frac{1}{3600}\text{h}}=72\frac{\text{km}}{\text{h}}$