Christopher needs 200 'blocks' to complete a project.

For every purchase of 'blocks' 17% of the 'blocks' are 'taxed' and go into a community fund.

So if Christopher buys 200 'blocks' he will only receive 166 'blocks'.

What formula does Christopher need to use, to work out how many 'blocks' he needs to buy, in order to get the 200 'blocks' he needs to complete his project?

This should be an easy question to answer, I just didn't know what to type into google to get the answer. Thanks.