The whole number is hours, so that's 1 hr. Subtract 1 to give 0.666... and multiply by 60=40 min. The seconds will be zero. To solve in general: example 2.345 hr. Whole number is hrs: 2. Subtract 2: 0.345, multiply by 60=20.7; whole number is minutes: 20. Subtract 20: 0.7, multiply by 60=42; this is the number of seconds, so the conversion is 2hr:20m:42s.
Multiply through by 4: 4C=s(t-d); divide through by s: 4C/s=t-d; add d to each side: (4C/s)+d=t so t=(4C/s)+d. The brackets aren't absolutely necessary, but they prevent ambiguity in interpretation.