Twice the sum of a number x and 9 is equal to 12 less than the number x.  What is the value of x?

x = -30

Step-by-step explanation:

Let x be the number.

2(x + 9) = x - 12

Use distributive property of multiplication

2x + 18 = x - 12

Simplify by combining like terms

2x - x = -12 - 18

x = -30

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)

3100

step-by-step explanation: