Each month for 7 months, samuel mwos 3 lawns. how many more lawns does he need to mow before he has mowed 29 laws?

He needs to mow 8 more lawns

So you need to get to 29 lawns right? So 29 is a prime number and doesn't have three as a common factor. So you have to get down to the very last bit on how often he mows lawns in the seven months. 7/3 does that, it's not precise but it's a great estimation.

2.333=7/3

So every 2.33... months he mows a lawn. So what's 3's closest factor to 29? 27. So now do 7*9 as in the months and stuff. You get 27, already 27 months off the bat. Now then do 2.33...*2=4.66 months extra. 

Here it is, just in case you don't want to read this all.

7/3=2.33...

7*9=27

29-27=2          2*2.33...=4.66+27

31.66 more months