98+a=425
Subtract 98 from both sides;
98-98 + a= 425-98
a=327
M-708=292
Add 708 to both sides;
M-708+708= 292+708
M=1000
Just do inverse operation, where if you have a subtraction sign in front of a number, you add that same number to it, vice versa for addition. just make sure to do the same to the number on the other side of the equal sign though.
x-9=10
x-9+9 = 10+9
x=19
x+9=10
x+9-9 = 10-9
x=1
