Given the following equation:
[tex]5x+10y=-3[/tex]You know, based on the information given in the exercise, that it is a true equation. You can notice that the sum (the result of the Addition) of the terms on the left side of the equation, is:
[tex]-3[/tex]Then, knowing the above and having the following expression:
[tex]5x+10y+7[/tex]You can substitute the sum of the equation into the expression:
[tex](5x+10y)+7=-3+7[/tex]Finally, adding the numbers, you get that the value of the expression is:
[tex]=4[/tex]