Answer:
the amount left is 16.2
Explanation:
The computation of the amount of money spend is shown below;
Given that
Total money available $20
This week 10% would be put in piggy bank
and, in next week 10% of the money would be put again in piggy bank
So the money left is
= $20 - $20 × 10% - ($18 × 10%)
= $20 - $2 - $1.8
= $16.2
Hence, the amount left is 16.2