Step-by-step explanation:

I think, he made a mistake because the exponents have different values but then if you'll look at his results, he just wrote the same thing. If you want, you could post the original problem, and I'll solve it for you :)
Answer:
area of path is area of park with path - area of rectangular park
area of park =l x b= 45 x 30=1350 cm2
area of park with path is =45+2.5+2.5 x 30+2.5+2.5 = 1750cm2
area of path = 1750-1350=400 cm2
Step-by-step explanation:
1) £20
2) 18/4 * 7 = 31,5msquared
3) X= (3-1)/5 = 2/5 = 0.4
4) A(n) = 2 + 5n
5) t(3) = 6*3 + 2 = 20
18x
Simple as that. 18 times however many times she cuts the grass