We have the following steps applied to solve this expression:
[tex]\begin{gathered} 1)2+(-5)+15+(-3) \\ 2)2-5+15-3 \\ 3)2-20-3 \\ 4)2-17 \\ 5)-15 \end{gathered}[/tex]
The mistakes are made in steps 3 and 4, where the sum of the terms are done.
The sum did not respect the signs in the operation:
[tex]-5+15\neq-20[/tex]
The sum should have done like this:
[tex]-5+15=15-5=10[/tex]
The correct steps are:
[tex]\begin{gathered} 2+(-5)+15+(-3) \\ 2-5+15-3 \\ (2-5)+(15-3) \\ -3+12 \\ 12-3 \\ 9 \end{gathered}[/tex]
