The ratio of the number of laps Tonya swam last week to the number of laps Randy swam last week is 3:10. If Randy swam 84 MORE laps last week, how many did Tonya swim?

To understand the ratio, you must know that 3:10 means that each time Tonya swam 3 laps, Randy swam 10 laps, by this reason, to identify the total number of laps you can divide the total difference given in the exercise (84 laps) into the difference indicated by the ratio (10 - 3 = 7 laps):

84 / 7 = 12

This number obtained is the number of times the ratio had to be met so that the difference in laps swam was 84. Now, you must multiply the obtained value (12) by the number of laps from Tonya given in the ratio (3):

Tonya's total number of laps = 12 * 3
Tonya's total number of laps = 36 laps

As you can see, with the calculates, we obtained 36 laps in total. You could also do the iterations 12 times, subtracting the number of turns given by Tonya from the number of turns made by Randy and you would get the same result:

10 - 3 = 7
20 - 6 = 14
30 - 9 = 21
40 - 12 = 28
50 - 15 = 35
60 - 18 = 42
70 - 21 = 49
80 - 24 = 56
90 - 27 = 63
100 - 30 = 70
110 - 33 = 77
120 - 36 = 84