Answer:
The answer is 30%
Explanation:
Solution
Given that:
Project A
Project A costs = $350
Cash flows =$250 and $250 (next 2 years)
Project B
Project B costs =$300
Cash flow = $300 and  $100
Now what is the crossover rate for these projects.
Thus
Year	Project A    Project B	A-B        B-A
0            -350     -300        -50        50
1             250      300        -50        50
2             250      100         150       -150
IRR         27%      26%         30%      30%
So,
CF = CF1/(1+r)^1 + CF2/(1+r)^2
$-50 = $-50/(1+r)^1 + $150/(1+r)^2
r = 30%
CF = CF1/(1+r)^1 + CF2/(1+r)^2
$50 = $50/(1+r)^1 + $-150/(1+r)^2
r = 30%
Hence, the cross over rate for these project is 30%
Note:
IRR =Internal rate of return
CF =Cash flow
r = rate