Hello :
if : a <span>≡ 5 ( mod 7) ....(1)
b </span><span>≡ 6 ( mod 7) ...(2)
(1)×(2) : ab </span><span>≡ 30 ( mod 7)
</span>but : 30 = 7×4 + 2 ..... so : 30 ≡ 2 ( mod 7)
then : ab ≡ 2 ( mod 7)
Answer:
"There are 30 chairs in 5 rows. How many chairs are in each row?" Would be the correct story problem.