To solve this equation, isolate the variable for which you are solving (a) on one side of the equation and put everything else on the other side.

9a - y = -8a + 5y - 7
9a = -8a + 5y - 7 + y
9a + 8a = 5y - 7 + y
17a = 6y - 7
a = \( \frac{6y - 7}{17} \)
a = \( \frac{6y}{17} \) + \( \frac{-7}{17} \)
a = \(\frac{6}{17}\)y - \(\frac{7}{17}\)

To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

8a - 7a = 1a

To solve this equation, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)

3b(b - z)
3(1)(1 - 5)
3(1)(-4)
(3)(-4)
-12

To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

3a x 4b = (3 x 4) (a x b) = 12ab

An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite:

d° = b° + c°

To find angle c, remember that the sum of the interior angles of a triangle is 180°:

180° = a° + b° + c°
c° = 180° - a° - b°
c° = 180° - 65° - 58° = 57°

So, d° = 58° + 57° = 115°

A shortcut to get this answer is to remember that angles around a line add up to 180°:

a° + d° = 180°
d° = 180° - a°
d° = 180° - 65° = 115°