> For example, what if she was given 216 phones to fix per week, and she fixes 46 per day?
I'm sorry; I'm confused. In that case, the equation would say that there are P = 216 - 46d phones to fix after d days. This isn't the same equation as the given P = 108 - 23d, although its right-hand side is proportional to the right-hand side of the original.
(That is, I'd agree with you if we were given just the ratio (phones to fix per week)/(phones fixed per day), but we're given more than that. Perhaps it's important to notice that we are given an equation (left-hand side = right-hand side), not just a formula (right-hand side by itself).)
But the question never stated that 108 and 23 meant anything more than numbers you use in the formula. So, if she were given 216 phones per week, and she fixes 46 per day, then the formula would hold true.
So the question does not provide enough information to select the answer they have designated as correct.
(This is many days later and I no longer have the question in front of me, and I'm not willing to invest the time to find it. But this was my thinking when I posted this).
I'm sorry; I'm confused. In that case, the equation would say that there are P = 216 - 46d phones to fix after d days. This isn't the same equation as the given P = 108 - 23d, although its right-hand side is proportional to the right-hand side of the original.
(That is, I'd agree with you if we were given just the ratio (phones to fix per week)/(phones fixed per day), but we're given more than that. Perhaps it's important to notice that we are given an equation (left-hand side = right-hand side), not just a formula (right-hand side by itself).)