8th grade math need help on a problem

Question

a substance has a mass of 500 grams. every year the substance decays by 2t grams , where t represents the number of years. What is the mass of the substance after 5 years ? 

 

 

show your work

Answer 1

m represents the mass

t represents time

 

m = 500 - 2t

 

After 5 years (t = 5)

m = 500 - 2(5)

 

How much mass is left?