Answer:
580 seedlings altogether.
Step-by-step explanation:
Given that,
Ali plants 40% of the total number of seedlings, Ben plants 45% of the total number of seedlings, and Cliff plants the rest of the seedlings. Cliff plants 87 seedlings.
The percentage of the seedling planted by Cliff = 100% - 45% - 40% = 15%
Let x = the total number of seedlings
[tex]15\%\ of\ x=87\\\\x=\dfrac{87\times 100}{15}\\\\x=580[/tex]
Hence, three boys plant 580 seedlings altogether.