Answer:
78
Step-by-step explanation:
For every 1 bout Lina makes, Harry makes two boats.
1 + 2 is 3.
117 divided by 3 = 39, which is how many boats Lina made.
39 x 2 = 78, which is how many boats Harry made.
To check our answer, 39 + 78 = 117, which is how many boats they made altogether, so the answer is correct.
