Ann goes swimming regularly. She wants to
Improve her fitness, 30 she decides to swim 10
lengths in the first session and increase the
number of lengths she swims by 2 every
session. When she reaches 50
lengths in a session she will not increase the
number any further. If Ann asks her friend Joy to
come swimming with her. Joy starts coming at
Sue's 5th session. Joy starts to swim 15 lengths
and increases the number of the lengths hy 5
each time. After how many of Joy's sessions
does she swim the same number of lengths as
Ann?
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