I need it fast
Find the value​

z = 4, x = 6

Step-by-step explanation:

(a)

= 7 ( multiply both sides by 3 to clear the fraction )

5z + 1 = 21 ( subtract 1 from both sides )

5z = 20 ( divide both sides by 5 )

z = 4

(b)

+ 3 = x + 7 ( multiply through by 3 to clear the fraction )

5x + 9 = 3x + 21 ( subtract 3x from both sides )

2x + 9 = 21 ( subtract 9 from both sides )

2x = 12 ( divide both sides by 2 )

x = 6

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)

54 kilometers per hour

step-by-step explanation:

according to rules:

1 km = 1000 meter

which means that 1 meter = 1/1000 km

1 hour = 3600 second [ as 1 hour = 60 min = 60 *60 seconds ]

which means that 1 second = 1/3600 hour

therefore, 1 kilometer/hour =

thus to convert 15 meter per second to kilometer per hour, we multiply 15 to 3.6 kilometer/hour.

15 meter/second=   which is the required answer.