The dangers that scientists face when they study volcanoes is the danger of being killed by the hot lava if it erupts so they put their life at risk by studying these dangerous natural disaster.
A hurricane is a violent wind in nature
or
A hurricane is a violent storm in nature
The answer is 65. Try doing it as an equation: 75-10=55+10
The union needed the help of African-American soldiers if they were to win the war. By releasing the emancipation proclamation, Abraham Lincoln declared that all slaves in Confederate territories would be free. Since they were now theoretically free, if the Union army managed to reach areas where there was a lot of former slaves, they would now be able to join the army and help free other slaves. They were no longer property that belonged to the slave owners, but free people who would fight slavery in the army.