Peter is buying 4 calculators to donate to his class. each calculator costs $9. he is also buying a $1 bottle of water for himself. he thinks his total will be $37. which expression could be used to estimate the reasonableness of peter’s total? 4 × $1 â€"" $1 4 × $1 $9 4 × $10 â€"" $9 4 × $10 $1