Aaa I thought this was a question and was ready to get into full answering mode lol
Answer:
9a+6b
Step-by-step explanation:
4a+7b+5a-b
First figure out the a's 4a + 5a = 9a
Then do b's (Remember, if there is no number by the letter then it is 1)
7b - 1b = 6b
So for this to be simplified the answer is 9a+6b
<span>The doubling time is the period of time
required for a quantity to double in size or value. It is applied to
population growth, inflation, resource extraction, consumption of goods,
compound interest, the volume of malignant tumours, and many other
things that tend to grow over time.</span>