A = (a+b)/2
2*A = 2*(a+b)/2 ... multiply both sides by 2
2A = a+b
2A-a = a+b-a ... subtract 'a' from both sides to isolate b
2A-a = b
b = 2A-a
Answer: b = 2A-a
Answer:
The answer is <u>D: lll and IV only</u>
Step-by-step explanation:
The cost of each pen is $50, because you spend $600 on books leaving $200 to buy FOUR pens, making it $50 per pen