Use the site called Desmos, it's a graphing calculator and should help you in all the ways you need. It isn't complex. Just put that equation in a box and it graphs it for you.
-7
-(-7) is 7 because two negative signs result in a positive. The opposite integer of 7 is -7
0.43 =
3/100 = 0.03
+
4/10 = 0.4
0.03 + 0.4 = 0.43.
Hope this helped☺☺
30 is the answer
i can help if need be