Kinetic energy is the part of total relativistic energy left after subtracting rest energy, so a faster object has more of its budget in the kinetic column. The total energy 125 J minus rest energy 100 J leaves kinetic energy 25 J exactly for the stated toy energy ledger; real measurements carry mass uncertainty, speed calibration, energy resolution, and unit-conversion limits.
Kinetic energy appears as the difference between total and rest energy. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Total energy contains the rest part
Total energy is 125 J and rest energy is 100 J.
E=125Erest=100
Kinetic energy is the extra part
Subtracting rest energy leaves kinetic energy 25 J.