3x - 6y = 20
-6y = -3x + 20
y = 1/2x - 20/6.....slope = 1/2...y int = -20/6 = -10/3
2x - 4y = 3
-4y = -2x + 3
y = 1/2x - 3/4..slope = 1/2...y int = -3/4
same slope, different y int = parallel lines = no solution = inconsistent

1) Since this is a Continuously Compounded operation in a 10 yrs period, then we can write out the following equation:

2) Plugging into the equation the given data and since Otto is 20 yrs old and he plans to get $4,000 in ten years, we can write out:

3) Thus the rate Otto needs is

Note that since the 0.1386 the six here is greater than 5 then we can round up to the next thousandth, in this case: 0.139. For the 0.1386 is closer to 0.139 (0.004) than to 0.138 (0.006).
Or 13.9%