6/9 is in 2/3 all you do is multiply numerator and denominator by 3
7.70 and 7.700 they are all the same since the 7 tenths are still in its place
Answer
Find out the conversion factor for seconds to minutes and convert 135 seconds to minutes.
To prove
1 minute = 60 second
for seconds to minutes.

Therefore the conversion factor for seconds to minutes be

Now convert 135 seconds to minutes.

= 2.25 minutes
Hence proved
the variable a would be 4