Question 1200683
85 is equal to 85% of the grade.
the final is equal to 15% of the grade.
the best he could do on the final is 100.
.85 * 85 + .15 * 100 = 87.25.
that's the best grade he can get, if the best grade he can get on a test is 100.


to earn a 75 for the course, you get:
.85 * 85 + .15 * x = 75
subtract .85 * 85 from both sides of the equation to get:
.15 * x = 75 - .85 * 85
divide both sides of the equation by .15 to get:
x = (75 - .85 * 85) / .15
solve for x to get:
x = 18.333333...... = 18 + 1/3 = 55/3.
.85 * 85 + .15 * 55/3 = 75.


those are the solutions that i believe you are looking for.