Applications of linear equations

Question

A group of scientists studied the effect of a chemical on various strains

of bacteria. Strain A started with

9000

cells and decreased at a constant rate of

3000

cells per hour after the chemical was applied. Strain B started with

4000

cells

and decreased at a constant rate of

2000

cells per hour after the chemical was

applied. When will the strains have the same number of​ cells? Explain.

Answer 1

9000 - 3000t = 4000 - 2000t

Can you solve for t and answer?