The tool that settles it cleanly is rank. Compare the rank of the coefficient matrix A with the rank of the augmented matrix [A|b]. Equal ranks means consistent, and the number of free variables is (number of unknowns − rank). Different ranks means you have a row like 0 0 0 | 5 and there is no solution at all.
One shake is not living on shakes. A single scoop in oats or in coffee is 24g for about 120 calories and takes ten seconds. I resisted for ages on principle and it turned out the principle was costing me an hour of cooking a week.
0 = 0 is literally what I got on attempt three and I assumed I had made a sign error. Kept both u choices as the trig function this time and it fell out in about two minutes. Thank you.
Check your database entries too. App entries are user submitted and some of them are simply wrong, occasionally by a factor of two. I found a bread entry logging a 45g slice as 60 calories when the packet said 120. Prefer entries that match the barcode on the actual product and spot check against the label once.
Also worth checking the boring possibilities before the clever ones. Is the afternoon hunger real hunger or is it boredom, stress or dehydration at a predictable time of day? Mine turned out to be 3pm at a desk with nothing interesting happening, and a glass of water and a ten minute walk handled a decent chunk of it.
Use the secure message centre rather than the phone for the first contact. You get a written record with a timestamp, which matters if you have to escalate later, and the person answering messages is usually looking at the same screens as the phone agent. If the answer is unsatisfactory, then call.
Always read the per 100g column rather than per serving. Serving sizes are chosen by the manufacturer and a serving of crackers is frequently four crackers, which nobody eats. Per 100g is the only figure you can compare between products.
Small thing that fixed prep boredom for me: cook the protein plainly and season at the point of eating. Marinated chicken tastes stale by Wednesday, plain chicken plus a fresh sauce does not. Applies to grains too, they keep far better unsalted and undressed.