1. Because it can help to increase your strength and energy, giving you more efficient muscles and a stronger heart.
2. People with back problems might go cycling because it doesn't make them carry the weight of their body on their feet.
3. If you do it too quickly you can have bad effects.
4. Twice or three times a week.
5. If you find you are in pain, you should stop and take a rest.

B. I really enjoyed the festival

mắ đó giờ mới dc 52 coin thôi ư :}?

yet
last
so far
at 6 o'clock
ago

\(a,\)\(100:5^2+7\cdot2^3\)
\(=100:25+7\cdot8\)
\(=4+56\)
\(=60\)
\(b,\)\(2^3\cdot15-\left[149-\left(12-5\right)^2\right]\)
\(=8\cdot15-\left[149-7^2\right]\)
\(=120-\left[149-49\right]\)
\(=120-100\)
\(=20\)

738cm

The pill is too big for the boy to swallow.
It is too late for us to go to the movie.
It is too cold for us to go swimming.

Bài 1:
\(a,3^6:3^2=3^{6-2}=3^4\)
\(b,5^{2012}:5^{2012}=5^{2012-2012}=5^0=1\)
\(c,25^4:5^2=\left(5^2\right)^4:5^2=5^8:5^2=5^{8-2}=5^6\)

Bài 2: 
\(2^2\cdot16:2^3\)
\(=4\cdot16:8\)
\(=8\)

Bài 3:
\(a,\) \(3^5\cdot9:243\)
\(=3^5\cdot3^2:3^5\)
\(=9\)
\(b,\) \(2^4:2\cdot8\)
\(=2^3\cdot8\)
\(=8\cdot8\)
\(=64\)
\(c,\) \(25^2\cdot25^3:125\cdot5^2\)
\(=\left(5^2\right)^2\cdot\left(5^2\right)^3:5^3\cdot5^2\)
\(=5^4\cdot5^6:5^3\cdot5^2\)
\(=5^9\)

Bài 4:
\(a,\) \(42\cdot57+43\cdot42-600\)
\(=42\cdot\left(57+43\right)-600\)
\(=42\cdot100-600\)
\(=4200-600\)
\(=3600\)
\(b,\) \(2^2\cdot5^2-64:2^3\)
\(=10^2-64:8\)
\(=100-8\)
\(=92\)

Bài 5:
\(a,\) \(91-5\cdot\left(5+x\right)=61\)
\(\Rightarrow5\cdot\left(5+x\right)=91-61\)
\(\Rightarrow5\cdot\left(5+x\right)=30\)
\(\Rightarrow5+x=30:5\)
\(\Rightarrow5+x=6\)
\(\Rightarrow x=6-5\)
\(\Rightarrow x=1\)

\(b, [(x+34)-50]\)\(\cdot2=56\)
\(\Rightarrow\left(x+34\right)-50=56:2\)
\(\Rightarrow\left(x+34\right)-50=28\)
\(\Rightarrow x+34=28+50\)
\(\Rightarrow x+34=78\)
\(\Rightarrow x=78-34\)
\(\Rightarrow x=44\)

4. spend + Ving 
to find out => finding out

a, 980
b, 580
c, 980

Vì 12124 ; 236 ; 1128 đều chia hết cho 2 => A ⋮ 2
Vì 97125 ; 245 ; 2590 đều chia hết cho 5 => B ⋮ 5
Vì 120 ; 3460 ; 1960 đều chia hết cho cả 2 và 5 => C ⋮ 2 và 5