Question 841572
12 minutes is 1/5 of an hour.
In 12 minutes Ralph goes 10 miles at 50 miles an hour
Since Mrs Ralph goes 10 miles (60-50) an hour faster than Ralph, it will take her an hour to catch up.

r*t=d
Ralph's time is t+1/5
Mrs Ralphs time is t

(t+1/5)*50=t*60
50t+10=60t
10=10t
t=1