Firstly, we want to get the cost of a decorated cost with 150 slices
From the question, we are told that the charge per slice for baking is $1.75
The cost of baking the 150 slices is thus;
[tex]150\times1.75\text{ = \$262.50}[/tex]The cost of decorating the cake per slice is $x
So the cost of decorating the 150 slices will be;
[tex]150\text{ }\times\text{ x = \$150x}[/tex]Thus, the total cost for the decoration will be;
[tex]262.50\text{ + 150x = \$(262.50 + 150x)}[/tex]Now, we have that the cost of decoration per slice. We simply replace the value x by 0.35
Thus, we have the total as;
[tex]\text{ \$(262.5 + 150(0.35)) = \$(262.5 + 52.5) = \$315}[/tex]