A variable is a letter, for example x, y or z, that represents an unspecified number.
6 + x = 12
To evaluate an algebraic expression, you have to substitute a number for each variable and perform the arithmetic operations. In the example above, the variable x is equal to 6 since 6 + 6 = 12.
Lets x = missing angle
x = 180 - (60+80)
x = 180 - 140
x = 40
answer
40
Answer:

Step-by-step explanation:
1. Divide the coefficients and the exponentials separately

2. Divide the coefficients

3. Divide the exponentials
Subtract the exponent in the denominator from the exponent in the numerator.

4. Re-join the new coefficient and the new exponential

5. Put the new number into standard form
The number before the power of 10 must be greater than or equal to one and less than 10.
Multiply the answer by 10/10.

Step-by-step explanation:
Given r = 12, s = 5,
