D = R × T
Distance = Rate × Time
"DRT triangle" — cover one to find it
UNIT RATE
Always divide to find "per 1"
$/item, miles/hour, pages/min
WORK = R × T
Combined rate: add individual rates
Together = 1/A + 1/B
PROPORTION
Cross-multiply to solve
a/b = c/d → ad = bc
AVG SPEED
Total Distance ÷ Total Time
NOT average of two speeds!
SCALING
Set up ratio, keep same units
Check: does answer make sense?