I always get confused with this kind of math problem, How do we solve this problem?
Example:
1 * 5 - 10 + 2 = ?
Solution 1 [My solution]:
Of couse I use MDAS rule
(1 * 5) - 10 + 2
5 - (10 + 2)
5 - 12
-7
Solution 2 [My prof]:
(1 * 5) - 10 + 2
5 (-10 + 2)
5 - 8
-3
The difference in our soution is I did not include the subtraction sign and my prof include it what is the rules in solving that kind of problem?
Your 1st solution is wrong : in $5-10+2$, $5-10$ is before $10+2$ so $$5-10+2 = (5-10)+2 = -5+2 = -3$$
When you have only additions and substractions, priority rule is given by the order of appearance of the different operations from left to right.