There are many different ways to write this sentence. Here are a couple of possible ways:
"The sum of 10 and 8 is 18"
"10 plus 8 equals 18"
Answer: b) 160 c) 1500
Step-by-step explanation: b) 50 + 50 + 30 + 30 = 160 c) 50 x 30 = 1500
The Greatest Common Factor (GCF) is very important when factoring. Later on, you will forget to pull out a GCF and the answer will be wrong. Always look for a GCF before doing anything.
Let's try factoring these:
a.) 
The greatest common factor of this expression is 9, because it is the maximum number that both can go into. Let's solve.

This is the simplest this expression can get. This would be your final answer. Let's try the other one.
b.) 
The GCF of this one is 12. Let's simplify it.

This is also the simplest you can get it. You can do nothing further. So, your final answers are:
a.) 
b.) 
Answer:
Step-by-step explanation:
198 is not a perfect square
Answer:
The left one and middle one
Step-by-step explanation:
same angles and length-width ratios