Inverse operation is an operation that undoes what was done by the previous operation. Take this simple addition problem 5+2=7. If we want to reverse the addition, we just subtract 7-2=5 and we are back where we started. You do the same for multiplication and division.
Interior angles on parallel lines cut by a traversal are supplementary (they add up to 180°). These can be identified as "c" angles, due to their shape. Knowing this, we can figure out the value of x:
7x+(2x+36)=180
7x+2x+36=180
Simplify the equation
9x+36=180
Collect like terms
9x=144
Divide by 9 on both sides to isolate x
x=16
The Answer is b: x = 18, y = -20
Proof:
Solve the following system:
{4 x + 3 y = 12 | (equation 1)
{7 x + 5 y = 26 | (equation 2)
Swap equation 1 with equation 2:
{7 x + 5 y = 26 | (equation 1)
{4 x + 3 y = 12 | (equation 2)
Subtract 4/7 × (equation 1) from equation 2:
{7 x + 5 y = 26 | (equation 1)
{0 x+y/7 = (-20)/7 | (equation 2)
Multiply equation 2 by 7:
{7 x + 5 y = 26 | (equation 1)
{0 x+y = -20 | (equation 2)
Subtract 5 × (equation 2) from equation 1:
{7 x+0 y = 126 | (equation 1)
{0 x+y = -20 | (equation 2)
Divide equation 1 by 7:
{x+0 y = 18 | (equation 1)
{0 x+y = -20 | (equation 2)
Collect results:
Answer: {x = 18, y = -20
