A student in a Pre-Calculus class has test scores of 68, 79, 78, and 63. The final exam is worth 3 test grades. Write a linear equation that models this problem, where x is the grade on the final exam and y is the student's grade in the course.
If x is the grade on the final exam, then it is equivalent to having three x's.
(68 + 79 + 78 + 63 + 3x)/7 = y = average grade
\({3x + 288\over7} = y\)
