Which equation represents a proportional relationship?

a) y = 2/5x

b) y = 1/3x + 5

c) y = −3x − 1

d) y = 2x + 0.5

A

Step-by-step explanation:

The equation of a proportional relationship has the form

y = kx ← k is the constant of proportionality.

The only one fitting this description is

y = x → A

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)

lockers 1, 4, 9, 16, 25, 40, and 49 are open

i ran through it by the other answer is wrong