3(a+1)=7(a-9)

Solution for 3(a+1)=7(a-9) equation:

Simplifying
3(a + 1) = 7(a + -9)

Reorder the terms:
3(1 + a) = 7(a + -9)
(1 * 3 + a * 3) = 7(a + -9)
(3 + 3a) = 7(a + -9)

Reorder the terms:
3 + 3a = 7(-9 + a)
3 + 3a = (-9 * 7 + a * 7)
3 + 3a = (-63 + 7a)

Solving
3 + 3a = -63 + 7a

Solving for variable 'a'.

Move all terms containing a to the left, all other terms to the right.

Add '-7a' to each side of the equation.
3 + 3a + -7a = -63 + 7a + -7a

Combine like terms: 3a + -7a = -4a
3 + -4a = -63 + 7a + -7a

Combine like terms: 7a + -7a = 0
3 + -4a = -63 + 0
3 + -4a = -63

Add '-3' to each side of the equation.
3 + -3 + -4a = -63 + -3

Combine like terms: 3 + -3 = 0
0 + -4a = -63 + -3
-4a = -63 + -3

Combine like terms: -63 + -3 = -66
-4a = -66

Divide each side by '-4'.
a = 16.5

Simplifying
a = 16.5