Can someone help me please?

1) 15.7 + (-3.45)
Adding a negative number is the same thing as subtracting, so 15.7 + (-3.45)= 12.25
2) -18.54 - (-32.05)
Subtracting a negative number is the same as adding (think of it as a double negative), so, it is the same thing as -18.54 + 32.05, which is equal to 13.51
3) -9.8 * 6.75
A negative number times a positive number is always negative, so -9.8 * 6.75= 66.15
4) 4/-0.5
Dividing by a negative number will always yield a negative quotient, so 4/-0.5 equals -8
Brainliest answer please.