<u><em>Answer:</em></u>
Dory biked 143 miles last month
<u><em>Explanation:</em></u>
Assume that Karly biked x miles last month
We are given that Dory biked 11 times as many miles as Karly did
<u>This means that:</u>
Dory biked 11x miles last month
<u>Now, we are given that:</u>
Together they biked a total of 156 miles
<u>Therefore:</u>
156 = x + 11x
156 = 12x
x = 13
<u>Based on the above:</u>
Karly biked x miles = 13 miles
Dory biked 11x miles = 11*13 = 143 miles
Hope this helps :)