9x - 5y = 29....when x = 1
9(1) - 5y = 29
9 - 5y = 29
-5y = 29 - 9
-5y = 20
y = 20/-5
y = -4 <==
N:7=x remainder 2
⇒ n= 7*x +2
4n= 4*(7x+2)=28x+8=28x+7+1=7*(4x+1)+1
⇒ the remainder is 1

When you have exercices like this tipe you write the base and add the exponents.the exponents are: 2; -4 and 5 so you put them in a sum:
2+ (-4) + 5=
=2 -4+5=
=7 -4=
=3
Answer:
The second one is D.
Step-by-step explanation:
Answer:
23 years
Step-by-step explanation:
Step 1: Calculate the rate constant (k) for the radioactive decay
A radioactive substance with initial concentration [A]₀ decays to 97% of its initial amount, that is, [A] = 0.97 [A]₀, after t = 1 year. Considering first-order kinetics, we can calculate the rate constant using the following expression.
ln [A]/[A]₀ = - k.t
k = ln [A]/[A]₀ / -t
k = ln 0.97 [A]₀/[A]₀ / -1 year
k = 0.03 year⁻¹
Step 2: Calculate the half-life of the substance
We will use the following expression.
= ln2/ k = ln 2 / 0.03 year⁻¹ = 23 years