A scientist studying fertilizer determines that an acre of corn needs 80 pounds of fertilizer on week 0, immediately before it is planted. For each additional week after planting, the amount of fertilizer added to the acre of corn that week can be reduced by 5 pounds. If this
relationship is plotted on the xy-coordinate plane, where x is the number of weeks after the corn is planted and y is the amount of fertilizer
used that week, what is the x-intercept of the graph?