You have 100 grams of sugar. Each sugar cookie requires 20 grams of sugar. Each peanut butter cookie requires 15 grams of sugar. If x = the number of sugar cookies you make, and y = the number of peanut butter cookies you make, which equation represents the combinations of sugar and peanut butter cookies you can make?

20x + 15y = 100

Like many students at university, you may be unhappy about the results you attain in exams. you may feel that even with all you are doing there must be something more -- or different-- you could be doing to get better grades. we have all at some time or other heard of that student who only studies a couple of hours for final exams and scores a's every time. we stand in awe of those who seem to breeze through without undue effort and seem to need very little in the way of studying to nail an exam. the reasons for success, in what i think are the vast majority of cases, are less esoteric than many students think: successful students consistently apply a series of productive strategies with view to attaining clearly identified learning and grade goals throughout the academic term.