$\text{a)}-{45}^{\circ }\text{C}>-{133}^{\circ }\text{C}>-{163}^{\circ }\text{C}$  

$\text{b)}$  

Mars:

${27}^{\circ }\text{C}-\left(-{133}^{\circ }\text{C}\right)={27}^{\circ }\text{C}+{133}^{\circ }\text{C}={160}^{\circ }\text{C}$  

Wenus:

${464}^{\circ }\text{C}-\left(-{45}^{\circ }\text{C}\right)={464}^{\circ }\text{C}+{45}^{\circ }\text{C}={509}^{\circ }\text{C}$  

Merkury:

${400}^{\circ }\text{C}-\left(-{163}^{\circ }\text{C}\right)={400}^{\circ }\text{C}+{163}^{\circ }\text{C}={563}^{\circ }\text{C}$