Hey there!!
To find the time for 65 messages to be sent, let's first find the number of messages sent in 1 min.
Hence, we will have to divide 52 and 8
... 52/8
... 6.5
We know that 6.5 messages are sent in 1 min.
Let's take the number of minutes as 'x'.
Then,
... 6.5x = 65
... x = 65/6.5
... x = 10
Another method:
We could take ratios.
... 52/8 = 65/x
... 52x = 65(8)
... 52x = 520
... x = 520 / 52
... x = 10
Hence, the number of minutes is 10.
Hope it helps!