Solve the system using elimination. 5 x + 4 y = 12 3 x – 3 y = 18

x = 4 , y = -2

Step-by-step explanation:

Solve the following system:

{5 x + 4 y = 12 | (equation 1)

3 x - 3 y = 18 | (equation 2)

Subtract 3/5 × (equation 1) from equation 2:

{5 x + 4 y = 12 | (equation 1)

0 x - (27 y)/5 = 54/5 | (equation 2)

Multiply equation 2 by 5/27:

{5 x + 4 y = 12 | (equation 1)

0 x - y = 2 | (equation 2)

Multiply equation 2 by -1:

{5 x + 4 y = 12 | (equation 1)

0 x+y = -2 | (equation 2)

Subtract 4 × (equation 2) from equation 1:

{5 x+0 y = 20 | (equation 1)

0 x+y = -2 | (equation 2)

Divide equation 1 by 5:

{x+0 y = 4 | (equation 1)

0 x+y = -2 | (equation 2)

Collect results:

 {x = 4 , y = -2

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)