Question

for the max sat problem if clause $1=$ not$(x1)$ or $x2$ or not$(x4),$ clause $2=$ not$(x2)$ or $x3$ or not$(x4),$ clause $3=x1$ or not$(x2)$ or $x3$ and clause $4=x2$ or not$(x3)$ or not$(x4)$ if $x1=$ false what is the expected number of clauses that expected to be satisfied given each variable is independently assigned true or false with probability $\frac{1}{2}.$ For $x1=$ true the correct answer $3\mathrm{.}75$ the solution says the number satisfied is $2**\frac{7}{8}=1\mathrm{.}75$ leaving and expected number of $3\mathrm{.}75.$ I am not sure how this is obtained. Please show your work