For what value of x must abcd be a parallelogram? asap

x = 3

Step-by-step explanation:

In a parallelogram, opposite sides have the same length. Then:

segment DC = segment AB

and

segment DA = segment CB

Replacing with data from the picture, we get:

18*x - 5 = 15*x + 4

18*x - 15*x = 4 + 5

3*x = 9

x = 9/3

x = 3

step-by-step explanation: a reaction is first order. if the initial reactant concentration is 0.0200 m, and 25.0 days later the concentration is 6.25 x 10-4 m, then its half-life is:

560

hope this : )