Answer:
2h 5min
Step-by-step explanation:
1 class: 25 min
5 classes: 25 x 5 = 125 min = 2h 5min
Since we know that
(a+b)
2
=a
+2ab+b
(a−b)
−2ab+b
Now,
(i)
(x+3y)
=x
+2×x×3y+(3y)
+6xy+9y
(ii)
(2x−5y)
=(2x)
−2×2x×5y+(5y)
=4x
−20xy+25y
(iii)
(a+
5a
1
)
+2×a×
2a
+(
+1+
4a
(iv)
(2a−1a)=(1a)
(1a)
=1a
Answer
Answer: The answer is that he cleaned one room
Because he charged in total 77 dollars and he charged 77 dollars per room, so 77*1=77=c
