Step 1

a) 90

Here the number of bottles are less than 120.

\(\displaystyle\Rightarrow\text{Price of each bottle is}\${2.50}\)

\(\displaystyle\Rightarrow\text{The price of 90 bottles is,}\)

\(\displaystyle{\left({90}\right)}\times{\left(\${2.50}\right)}=\${225}\)

b) 120

The number of bottles are 120.

\(\displaystyle\Rightarrow\text{Price of each bottle is}\${2.50}\)

\(\displaystyle\Rightarrow\text{The price of 120 bottles is,}\)

\(\displaystyle{120}\times{\left(\${2.50}\right)}=\${300}\)

c) 150

Here the number of bottles are more than 150.

\(\displaystyle\Rightarrow\text{Price of each bottle is}\${2.25}\)

\(\displaystyle\Rightarrow\text{The price of 150 bottles is,}\)

\(\displaystyle{\left({150}\right)}\times{\left(\${2.25}\right)}={337.5}\)