Evaluate the expression when x = – 8, y = 4 and z = – 5

x + y

The addition is a process of adding two or more items together. In math, addition is the method of calculating the total of two or more numbers to know the sum of the numbers.

An example of addition is: 5 + 11 + 3 = 19.

Example: If a = 7 and b = 8, find the value of a + b

To evaluate the expressiona + b, substitute the value of a as 7 and the value of b as 8 and add the numbers as shown below,

$a+b=7+8=15$

Rule: If they are with the opposite sign (one is positive and other is negative), subtract the smaller number from the bigger number ignoring the sign, then put the sign of bigger number before the answer.

To evaluate the expression(x + y), substitute the value of x as – 8; y = 4 and subtract 4 from (– 8) and put the sign (negative) of the bigger number (– 8) before the answer.

When x = – 8; y = 4 and the expression (x + y) is$x+y=-8+4=-4$

Thus, the value of the expression is – 4.