to calculate

https://tts.langeek.co/read?text=dG8gY2FsY3VsYXRl&hash=87eda6e715ae15297914cfd0f623d4407a94b68b&lang=en&cache-only=0

Here you will find the vocabulary from Unit 10 in the Headway Intermediate coursebook, such as "fall out", "develop", "save up", etc.