a. is <u><em>Substitution Property</em></u>
b. might be <u><em>definition of supplementary angles</em></u>
For get the solution of this task, we must make the system of equations.First it: "The quotient between the sum of two numbers and one of them is equal to 3" Let's take two values: a and b.(a+b)/b=3 --- it's will be first equation in our system.
and "The inverse of double the sum of them and equal to 1/6"1/2(a+b)=1/6 it's will be second equation in our system.
Attention at parenthesis.
System(a+b)/b=31/2(a+b)=1/6
by the first equation:(a+b)/b=3a+b=3ba=2b --- we will use this equation for second equation in system
1/2(2b+b)=1/61/3b)=1/63b=6b=2 and a=2b, that's mean a=1.The answer is pair (1;2)
while solving an equation, use order of operations. An expression is a combinations of numbers, variables, and symbols to be calculated, while an equation contains expressions that are separated by equals sign.. it's the combination of two expressions so in the equation both expressions equal each other.