Answer:
(a) 8.15
(b) 12.92
Step-by-step explanation:
Given: P = $3000, r = 0.085

Where
A is the Amount
P is the Principal
r is the rate
t is the time
(a) For the amount to double, A = 2 × P
A = 2 × $3000
A = $6000



Take
of both sides

But 
∴ 


t = 8.15
(b) For the amount to double, A = 3 × P
A = 3 × $3000
A = $9000



Take
of both sides

But 
∴ 


t = 12.92
Answer:
(a-c)/b = x
Step-by-step explanation:
a = bx + c
subtract 'c' from each side to get:
(a-c) = bx
divide each side by 'b' to get:
(a-c)/b = x
The result would be 3x^2+7x+2.
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