The Given Sequence is an Arithmetic Sequence with First term = -19
⇒ a = -19
Second term is -13
We know that Common difference is Difference of second term and first term.
⇒ Common Difference (d) = -13 + 19 = 6
We know that Sum of n terms is given by : 
Given n = 63 and we found a = -19 and d = 6
The Sum of First 63 terms is 10521
The best estimate would be to assume that they all have an average number of petals.
An estimate of 1,938 petals
If the company makes 1 canoe only, then the cost is, the fixed cost plus how much it costs for the 1 canoe, or
180,000 + 1*120
if it makes 2 canoes
180,000 + 2*120
3 canoes 180,000 + 3*120
4canoes 180,000 + 4*120
x canoes 180,000 + x*120
so... we dunno what "x" is, but whatever "x" maybe, the cost ends up as 180,000 + x*120, or 180,000 + 120x
now, let's see the revenue
1 canoe 1 * 240
2 canoes 2*240
3 canoes 3*240
x canoes x*240
so.. whatever "x" maybe, the Revenue is x*240 or 240x
break-even point is when, the amount of expenses and earnings cancel each other out, or, there's no profit, but there's no loss either, same amount that's spent is also earned back
so, the break-even point occurs when Revenue = Cost
180,000 + 120x = 240x <--- solve for "x"
Just multiply 42 by 10 and that gives you 420 , so the real car has a length of 420cm or 4.2 metres :)
