Function for numeric input output series

Question

I am trying to find function which will give me output for corresponding inputs.

20      155
40      195
60      235
80      275
100     315
120     218
140     78
50      215
90      295
100     315
110      206
120     216
130     226
140     78
150     78
160     78
170     -112
180     -122
190     -132 

Can someone point which methods can help me achieve this?