Let's say hmm let's use the figures in thousands, so
model A costs 90 + 4 per year, so... ok.. after "t" years, then the cost for model A is then 90 + 4*t, or
A = 90 + 4t.
now, model B is 70 + 10 per year, so,... after "t" years, model B is then
B = 70 + 10 * t, or
B = 70 + 10t.
if we were to assume A < B, namely the cost of A is less than B, what would the years be? namely, what's "t"?

after that period, then A becomes cheaper than B.
D, it’s the only answer that equals 30. When splitting up the 6, you’re doing the distributive property, which is what D is doing.
Answer:
51 pounds, 48 pounds, 44 pounds and 40 pounds in that chronological order.