I'm not sure I understand the question. Is this worded correctly?
12 Pairs
4 pairs = 8
2 pairs = 4
8 + 4 = 12
If you need total socks, there's 24 total
Answer a = 5 and b = 2.
Procedure
Initially means x = 0, then
5 = a*b^0 = a*1 = a, then a = 5
When x = 1, the height is the double of 5, i.e 10 and
10 = a.b^1 = a.b ⇒ b = 10/a = 10/5 = 2
The a = 5 and b = 2, so the equation is y =5(2)^x
The Gradient would be negative therefore making it start by going down then up, making a sad mouth. the x intercepts will be the same. Frankly it just flipped upside down. I remember it like if the gradient is positive then happy smile, if its negative then sad smile. Hope I helped.