Answer:
138 is the answer
Step-by-step explanation:
128 square
You multiply 86 by 42.5 because each board is 42.5 and there are 86 boards.
When you multiply fractions you want to make them a mixed number then multiply the two top numbers together and then the bottom two together. Basically 6 2/3 would become 20/3 x 5/6... then multiply 5 and 20 together and 3 and 6 together to get 100/18... simplify from there.