Got it. Thank you.
Clear[x1, x2]
{{x1[t], x2[t2]}} = {x1[t], x2[t]} /.
DSolve[
{x1'[t] == 1 - 2.5 x1[t] + x2[t],
x2'[t] == 2 x1[t] - x2[t],
x1[0] == 0,
x2[0] == 0},
{x1[t], x2[t]}, t]
{{E^(-3.5 t) (-0.219131 E^(0.149219 t) +
4.4408910^-16 E^(0.298438 t) - 1.78087 E^(3.35078 t) +
2. E^(3.5 t) - 6.9388910^-18 E^(6.70156 t)),
E^(-3.5 t) (0.186433 E^(0.149219 t) -
4.44089*10^-16 E^(0.298438 t) - 4.18643 E^(3.35078 t) +
4. E^(3.5 t))}}
Those commas can really cause a considerable amount of frustration.
SUGGESTION, Maybe in future updates recommendations for commas may be suggested by Mathematica - Similar to Grammar and Spell Checks.
In addition, you may also collect some of these errors and have a puzzle section for possible corrections.
Thank you very very much.
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