At the end of every school year (starting with 1st grade), Sophie's grandparents added $75 into her college fund. At the end of 7th grade, her college fund had a total of $958. Which of these equation expresses the amount $\displaystyle{y}\usepackage{cmbright}\Huge\$ Sophie has in her college fund after she finishes grade $\displaystyle{x}\usepackage{cmbright}\Huge\$ ?